Engine Controls - 6.0L - Alternative Fuels (Introduction): Removal & Installation GMC Sierra 3500

Removal Procedure

1. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.
2. Remove enough of the forward right side wheelhouse panel retainers in order to gain access to the front of the wheelhouse. Refer to Wheelhouse Panel Replacement in Body Front End in the C/K Pickup Service Manual.
3. Loosen the fuel injection control module (FICM) mounting bracket screws (1).
4. Remove the connector position assurance lock and disconnect the electrical connector from the FICM.
5. Remove the lower right FICM mounting bracket screw (2).
6. Remove the FICM mounting bracket assembly (3) from the vehicle.
7. Remove the FICM insulator (3) mounting nuts (4).
8. Remove the FICM (2) from the mounting bracket (1).
9. Remove the insulators (3) from the FICM.

Installation Procedure

1. Install the FICM insulators (3) into the FICM (2). Tighten: Tighten the insulators fingertight.
2. Install the FICM (2) onto the mounting bracket (1) ensuring the connector is facing down.
3. Install the insulator nuts (4). Tighten: Tighten the nuts to 12 N.m (9 lb ft).
4. Slide the FICM mounting bracket (3) first onto one mounting screw (1) then onto the other mounting screw (1). Do not tighten the screws.
5. Install the lower right FICM mounting bracket screw (2). Tighten: Tighten all of the mounting screws to 12 N.m (9 lb ft).
6. Connect the electrical connector to the FICM and install the connector position assurance lock.
7. Install the right side wheelhouse panel retainers. Refer to Wheelhouse Panel Replacement in Body Front End in the C/K Pickup Service Manual.
8. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.

1. Relieve the CNG fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Remove the upper (1) and lower (3) tank cover (2) mounting bolts.
4. Remove the tank cover (2) from the vehicle.

1. Install the tank cover (2).
2. Loosely install all the tank cover bolts. Tighten: Tighten the bolts to 8 N.m (71 lb in).
3. Connect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.

1. If the tank is being removed in order to replace the high pressure lock-off (HPL) solenoid or for internal tank cleaning perform the «High Pressure Lock-Off (HPL) Solenoid Replacement»(ref-184498-S07282428232005082300000) instead of this procedure.
2. Relieve the CNG fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
3. If the tank is to be discarded or shipped it must be vented. Venting will damage the high pressure lock-off (HPL) solenoid. Refer to «Fuel Tank Venting Procedure»(ref-184498-S14125958572005082300000) .
4. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
5. Remove the fuel tank cover. Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .
6. Disconnect the high pressure lock-off (HPL) solenoid connectors (5, 7).
7. Disconnect the fuel tank pressure (FTP) sensor connector (1).
8. Disconnect the high pressure regulator (HPR) fuel inlet line (3).
9. Remove the HPR fuel inlet fitting (6). Capture the filter spring (4), filter (3) and seal (2) that are located behind the inlet fitting.
10. Remove the HPR mounting nut (1).
11. Disconnect the fuel line (4) from the tee fitting (3).
12. Disconnect the tee fitting (3) from the HPL fitting (2).
13. Disconnect the fuel line clips (4) at the lower tank cover mounting bracket.
14. Disconnect the fuel line clips (3) at the tank frame (3).
15. Remove the fuel filter mounting bolts (1).
16. Remove the fuel filter and line assembly from the vehicle.
17. Disconnect the HPR coolant hoses from the lower tank cover mounting bracket retainers.
18. Remove the lower tank cover mounting bracket bolts (2).
19. Set aside the mounting bracket assembly in order to gain access to the tank strap retaining nuts.
20. Remove the upper tank cover mounting bracket bolts (3).
21. Remove the upper tank cover mounting bracket (1).
22. Remove the tank strap retaining nuts (5).
23. Remove the tank strap upper mounting clips (6) and pins (1).
24. Remove the tank straps from the vehicle.
25. Place the J 45529 (1) around the tank (2). See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
26. Connect the J 45529 (1) to a suitable lifting device and remove the tank from the vehicle. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .

1. Lower the fuel tank (2) into the tank mounting frame ensuring that the high pressure lock-off solenoid is properly oriented to the fuel line.
2. Place the straps (2) around the tank.
3. Install the tank strap upper mounting pins (1) and clips (6).
4. Install the tank strap mounting nuts (5). Tighten: Tighten the tank strap mounting bolts to 47 N.m (35 lb ft).
5. Install the upper tank cover mounting bracket (1) and bolts. Tighten: Tighten the bolts to 8 N.m (71 lb in).
6. Slide the lower tank cover mounting bracket over the HPR and into position.
7. Install the lower tank cover mounting bracket and bolts (2). Tighten: Tighten the bolts to 50 N.m (37 lb ft).
8. Attach the HPR coolant hoses to the lower tank cover mounting bracket retainers.
9. Install the HPR mounting nut (1). Tighten: Tighten the nut to 54 N.m (40 lb ft).
10. Install the filter spring (4), filter (3) and seal (2) into the HPR inlet port.
11. Install the HPR fuel inlet line fitting (6) with a new O-ring. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line fitting to 48 N.m (35 lb ft).
12. Install the fuel filter and line assembly. Tighten: Tighten the bolts (1) to 27 N.m (20 lb ft).
13. Fasten the fuel line at the lower tank cover mounting bracket (4) and the tank strap (3).
14. Connect the fuel line (3) to the HPR fuel inlet fitting with a new O-ring face seal. Lubricate the O-ring face seal with petroleum jelly. Tighten: Tighten the fitting to 37 N.m (27 lb ft).
15. Connect the tee (3) to the HPL fitting (2) with a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fitting to 37 N.m (27 lb ft).
16. Connect the fuel line (4) to the HPL fitting (3) with a new O-ring face seal. Lubricate the O-ring face seal with petroleum jelly. Tighten: Tighten the fitting to 37 N.m (27 lb ft).
17. Connect the HPL solenoid connectors (5, 7).
18. Connect the FTP sensor connector (1).
19. Connect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
20. Fill the CNG fuel system.
21. Start the engine and use the J 45878 in order to inspect for CNG fuel system leaks at each serviced fitting. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
22. Install the fuel tank cover. Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .

1. If the tank is being removed in order to replace the high pressure lock-off (HPL) solenoid or for internal tank cleaning perform the «High Pressure Lock-Off (HPL) Solenoid Replacement»(ref-184498-S07282428232005082300000) instead of this procedure.
2. Relieve the CNG fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
3. If the tank is to be discarded or shipped it must be vented. Venting will damage the high pressure lock-off (HPL) solenoid. Refer to «Fuel Tank Venting Procedure»(ref-184498-S14125958572005082300000) .
4. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
5. Remove the truck body as required on ZW9 equipped vehicles in order to gain access to the CNG fuel tank.
6. Disconnect the high pressure lock-off (HPL) solenoid connectors (5, 7).
7. Disconnect the fuel tank pressure (FTP) sensor connector (1).
8. Disconnect the HPL fuel lines (1, 3).
9. Remove the tank strap retaining nuts (2).
10. Remove the clips (4) and pins (5) from the tank strap mounting bracket.
11. Remove the tank straps (1).
12. Place the J 45529 (1) around the tank (2). See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
13. Connect the J 45529 (1) to a suitable lifting device and remove the tank from the vehicle. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .

1. Lower the fuel tank (2) into the tank mounting frame with the J 45529 . See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
2. Place the straps (1) around the tank.
3. Ensure that the high pressure lock-off solenoid is properly oriented to the fuel line fittings.
4. Install the tank strap mounting pins (5) and clips (4).
5. Install the tank strap mounting nuts (7). Tighten: Tighten the tank strap mounting bolts to 47 N.m (35 lb ft).
6. Connect the fuel lines (1, 3) to the HPL fittings with new O-ring face seals. Lubricate the O-ring face seals with petroleum jelly. Tighten: Tighten the lines to 37 N.m (27 lb ft).
7. Connect the HPL solenoid connectors (5, 7).
8. Connect the FTP sensor connector (1).
9. Connect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
10. Fill the CNG fuel system.
11. Start the engine and use the J 45878 in order to inspect for CNG fuel system leaks at each serviced fitting. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
12. Install the truck body as required on ZW9 equipped vehicles.

1. Remove the CNG fuel tank. Refer to «Fuel Tank Replacement (Pickup with Type 2 Tank)»(ref-184498-S38086511632005082300000) or «Fuel Tank Replacement (Cab/Chassis with Type 2 Tank)»(ref-184498-S03879037722005082300000) .
2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information in the C/K Pickup service manual.
3. Remove the exhaust system heat shields.
4. Remove and discard the frame support bracket nuts (3).
5. Remove the frame support brackets (4).
6. Lower the vehicle.
7. Remove the CNG fuel tank mounting frame.
8. Discard the fuel tank frame mounting bolts.

1. Position the CNG fuel tank mounting frame into the bed using new mounting bolts.
2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information in the C/K Pickup service manual.
3. Install the frame support brackets (4) using new nuts (3). Tighten: Tighten the nuts to 81 N.m (60 lb ft).
4. Install the exhaust system heat shields and bolts. Tighten: Tighten the bolts to 9 N.m (80 lb in).
5. Install the CNG fuel tank. Refer to «Fuel Tank Replacement (Pickup with Type 2 Tank)»(ref-184498-S38086511632005082300000) or «Fuel Tank Replacement (Cab/Chassis with Type 2 Tank)»(ref-184498-S03879037722005082300000) .

1. Remove the CNG fuel tank. Refer to «Fuel Tank Replacement (Pickup with Type 2 Tank)»(ref-184498-S38086511632005082300000) or «Fuel Tank Replacement (Cab/Chassis with Type 2 Tank)»(ref-184498-S03879037722005082300000) .
2. Remove the fuel line hold-down clips (1, 4).
3. Disconnect the fuel line at the fuel filter inlet (2).
4. Disconnect the fuel line at the high pressure regulator (HPR) inlet (3).
5. Remove the fuel lines from the vehicle.
6. Remove the fuel filter bracket mounting bolts (2, 4)
7. Remove the fuel filter/fuel line assembly from the vehicle.
8. Partially drain the engine coolant. Refer to Draining and Filling Cooling System (with HP2) Draining and Filling Cooling System (without HP2) in Engine Cooling in the C/K Pickup Service Manual.
9. Loosen the hose clamps (2, 6) enough to move the clamps away from the HPR coolant fittings.
10. Disconnect the HPR coolant hoses (3, 5) from the HPR.
11. Pull the HPR coolant hoses through the tank mounting frame.
12. Disconnect the HPR fuel outlet line (4).
13. Remove the HPR fuel inlet fitting (6). Capture the filter spring (4), filter (3) and seal (2) that are located behind the inlet fitting.
14. Remove the HPR mounting nut (1) and washer.
15. Remove the HPR from the mounting bracket.
16. Remove and discard the tank mounting plate to vehicle frame bolts and nuts (1, 2).
17. Remove the CNG fuel tank mounting plate from the vehicle.

1. Position the CNG fuel tank mounting plate onto the vehicle.
2. Install the tank mounting plate to the vehicle frame with new bolts and nuts (1, 2). Tighten: Tighten the nuts to 110 N.m (81 lb ft).
3. Install the HPR assembly (8) to the mounting bracket.
4. Install the HPR mounting nut (1) and washer. Tighten: Tighten the nut to 54 N.m (40 lb ft).
5. Install the filter spring (4), filter (3) and seal (2) into the HPR inlet port.
6. Install the HPR fuel inlet line fitting (6) with a new O-ring. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line fitting to 48 N.m (35 lb ft).
7. Pull the HPR coolant hoses through the tank mounting frame.
8. Connect the HPR coolant hoses (3, 5) to the HPR.
9. Install the HPR fuel outlet line (4) with a new O-ring. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line fitting to 37 N.m (27 lb ft).
10. Install the fuel filter/fuel line assembly into the vehicle.
11. Install the fuel filter bracket mounting bolts (2, 4). Tighten: Tighten the bolts to 12 N.m (9 lb ft).
12. Install the HPR fuel inlet line (3) with a new O-ring. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line fitting to 37 N.m (27 lb ft).
13. Install the fuel filter inlet line (2) with a new O-ring. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line fitting to 37 N.m (27 lb ft).
14. Install the fuel line mounting clips (1, 4). Tighten: Tighten the check valve fuel line mounting clip bolt (4) to 12 N.m (9 lb ft).
15. Install the CNG fuel tank. Refer to «Fuel Tank Replacement (Pickup with Type 2 Tank)»(ref-184498-S38086511632005082300000) or «Fuel Tank Replacement (Cab/Chassis with Type 2 Tank)»(ref-184498-S03879037722005082300000) .
16. Fill the cooling system. Refer to Draining and Filling Cooling System (with HP2) Draining and Filling Cooling System (without HP2) in Engine Cooling in the C/K Pickup Service Manual.
17. Fill the CNG fuel system.
18. Start the engine and use the J 45878 in order to inspect for CNG fuel system leaks at each serviced fitting. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information in the C/K Pickup service manual. Remove the truck body or side panel as required on ZW9 equipped vehicles in order to gain access to the fill valve.
4. Disconnect the fill line (3) at the fill valve (2).
5. Remove the bolts (4) from the mounting plate (2).
6. Remove the fill valve mounting nut (3).
7. Remove the fill valve (2) from the vehicle.

1. Install the fill valve (2) into the mounting plate (1).
2. Install the fill valve nut (3). Tighten: Tighten the nut to 41 N.m (30 lb ft).
3. Install the mounting plate (2) to the fill housing with the attaching bolts (4). Tighten: Tighten the bolts to 8 N.m (6 lb in).
4. Connect the fill line (3) to the fill valve (2) with a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fitting to 37 N.m (27 lb ft).
5. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
6. Start the vehicle and inspect for CNG fuel leaks at the serviced fitting using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .

1. Remove the O-ring (1).
2. Remove the circlip (2).
3. Remove the fill valve filter (3).
4. Clean the filter in solvent.
5. Blow dry the filter using compressed air.
6. Be sure that the filter passages are clear. Replace the filter if needed.

1. Install the fill valve filter (3).
2. Install the circlip (2).
3. Install the O-ring (1).

1. Relieve the CNG fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Loosen the in-line CNG filter housing.
3. Unthread and remove the housing.
4. Remove the filter element (2) from the in-line CNG filter assembly (1) using a pulling and twisting motion.
5. Wipe out any oil or fluid residue from the inside of the filter housing.

1. Push the filter element (2) onto the in-line CNG filter assembly (1).
2. Install the filter housing into the in-line CNG filter assembly using a new O-ring. Lubricate the O-ring with petroleum jelly before installation. Tighten: Tighten the filter housing to 54 N.m (40 lb ft).
3. Cycle the ignition several times in order to build CNG fuel pressure.
4. Inspect for fuel system leaks at all serviced fittings.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.
3. Remove the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .
4. Disconnect the fuel tank pressure (FTP) sensor connector (1).
5. Remove the FTP sensor (2) from the high pressure lock-off (HPL) solenoid.

1. Install the fuel tank pressure (FTP) sensor (2) into the high pressure lock-off (HPL) solenoid with new O-ring. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel tank pressure sensor to 27 N.m (20 lb ft).
2. Connect the fuel tank pressure sensor (1) connector.
3. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.
4. Start the vehicle and inspect for CNG fuel leaks at the serviced fitting using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
5. Install the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.
3. Remove the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .
4. Partially drain the coolant or pinch off the high pressure regulator (HPR) coolant hoses (3, 5). Refer to Draining and Filling Cooling System (with HP2) Draining and Filling Cooling System (without HP2) in Engine Cooling in the C/K Pickup Service Manual.
5. Loosen the hose clamps enough to move the clamps (2, 6) away from the HPR coolant fittings.
6. Disconnect the HPR coolant hoses (3, 5) from the HPR.
7. Disconnect the HPR fuel inlet line (9).
8. Disconnect the HPR fuel outlet line (4).
9. Remove the HPR fuel inlet line fitting from the HPR. Capture the filter spring, filter and seal that are located behind the fuel inlet line fitting.
10. Remove the HPR mounting nut (1).
11. Remove the HPR from the mounting bracket.

1. Install the HPR assembly (8) to the mounting frame (7).
2. Install the HPR mounting nut (1). Tighten: Tighten the nut to 54 N.m (40 lb ft).
3. Connect the HPR fuel outlet line (4) using a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
4. Install the fuel inlet line fitting using a new O-ring. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line fitting to 48 N.m (35 lb ft).
5. Connect the HPR fuel inlet line (9) to the HPR fitting. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
6. Connect the HPR coolant hoses (3, 5) to the HPR.
7. Tighten the coolant hose clamp (6) ensuring that the clamp fastens the hose to the HPR fitting.
8. Remove the coolant hose pinch pliers if used.
9. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.
10. Fill the cooling system. Refer to Draining and Filling Cooling System (with HP2) Draining and Filling Cooling System (without HP2) in Engine Cooling in the C/K Pickup Service Manual.
11. Inspect the cooling system for leaks. Refer to Loss of Coolant in Engine Cooling in the C/K Pickup Service Manual.
12. Start the vehicle and inspect for CNG fuel leaks at the serviced fitting using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
13. Install the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Remove the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .
4. Disconnect the HPR fuel inlet line (9).
5. Disconnect the HPR fuel outlet line (4).
6. Remove the HPR fuel inlet line fitting from the HPR.
7. Remove the HPR mounting nut (1).
8. Remove the HPR from the mounting bracket.
9. Remove the HPR filter spring (4).
10. Remove the HPR filter (3).
11. Remove the seal (2).

1. Install the high pressure regulator (HPR) filter seal (2).
2. Install the HPR filter (3).
3. Install the filter spring (4).
4. Install the HPR assembly (8) to the mounting frame (7).
5. Install the HPR mounting nut (1). Tighten: Tighten the nut to 54 N.m (40 lb ft).
6. Connect the HPR fuel outlet line (4) using a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
7. Install the fuel inlet line fitting using a new O-ring. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line fitting to 48 N.m (35 lb ft).
8. Connect the HPR fuel inlet line (9) to the HPR fitting. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
9. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
10. Start the vehicle and inspect for CNG fuel leaks at the serviced fitting using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
11. Install the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .

1. Relieve the CNG fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Remove the fuel tank cover. Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) . Remove the truck body or side panel as required on ZW9 equipped vehicles in order to gain access to the right side of the CNG fuel tank.
4. Disconnect the high pressure lock-off (HPL) solenoid connectors (5, 7).
5. Vent the fuel pressure from the tank. Refer to «Fuel Tank Venting Procedure»(ref-184498-S14125958572005082300000) .
6. Remove the vent hose (6) from the HPL.
7. Remove the line fittings and discard the O-rings.
8. Remove the manual vent tool.
9. With the J 43602 loosen the HPL. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) . Proceed directly to Step 27 for vehicles equipped with the ZW9 option.
10. Disconnect the high pressure regulator fuel inlet line (3).
11. Remove the HPR fuel inlet fitting (6). Capture the filter spring (4), filter (3) and seal (2) that are located behind the inlet fitting.
12. Remove the HPR mounting nut (1).
13. Disconnect the fuel line clips (4) at the lower tank cover mounting bracket.
14. Disconnect the fuel line clips (3) at the tank frame (3).
15. Remove the fuel filter mounting bolts (1).
16. Remove the fuel filter and line assembly from the vehicle.
17. Remove the upper tank cover mounting bracket bolts (3).
18. Remove the upper tank cover mounting bracket (1).
19. Disconnect the HPR coolant hoses from the lower tank cover mounting bracket retainers.
20. Remove the lower tank cover mounting bracket bolts (2).
21. Set aside the mounting bracket assembly in order to gain access to the tank strap retaining nuts.
22. Remove the tank strap retaining nuts (5).
23. Remove the tank strap upper mounting clips (6) and pins (1).
24. Remove the tank straps from the vehicle.
25. Place the J 45529 (1) around the tank (2). See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
26. Connect the J 45529 (1) to a suitable lifting device and remove the tank from the vehicle. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
27. Unthread the HPL from the CNG fuel tank and discard the HPL and O-ring.
28. Inspect the inside of the CNG fuel tank for water, rust, or other contaminants.
29. If necessary, clean the CNG fuel tank. Refer to «Fuel Tank Cleaning»(ref-184498-S03366849632005082300000) .

1. Install the NEW O-ring on the HPL.
2. Lubricate the O-ring with petroleum jelly.
3. Ensure that the O-ring mating surface of the tank is clean and free of debris or damage.
4. Install the HPL in the tank and tighten hand-tight. Do not install the fuel line fittings. Proceed directly to Step 9 for vehicles equipped with the ZW9 option.
5. Lower the fuel tank (2) into the tank mounting frame ensuring that the high pressure lock-off solenoid is properly oriented to the fuel line.
6. Place the straps around the tank.
7. Install the tank strap upper mounting pins (1) and clips (6).
8. Install the tank strap mounting nuts (5). Tighten: Tighten the tank strap mounting bolts to 47 N.m (35 lb ft).
9. Tighten the HPL as specified below. Tighten: Tighten the HPL to a nominal torque of 305 N.m (225 lb ft) at 0 degrees. You must compensate for the torque wrench and the HPL crowfoot offset. Refer to the formula below for compensation of your torque wrench.
10. To obtain your dial reading perform the following procedure: Multiply your torque wrench length in inches by 305 (225). 18 inch torque wrench example: 18 X 305 = 5490. Add 3 to the length of your torque wrench. 18 inch torque wrench example: 18 + 3 = 21. Divide the first value obtained by the second value obtained. The result indicates the amount of torque your wrench should tighten the HPL to. 18 inch torque wrench example: 5490 divided by 21 = 261.4. For an 18 inch long torque wrench tighten the HPL to 261.4 N.m.
11. Install the HPL port fittings (4, 8) with new O-rings. Lubricate the new O-rings with petroleum jelly. Tighten: Tighten the fitting to 48 N.m (35 lb ft).
12. Install the fuel tank pressure (FTP) sensor (2) with a new O-ring. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the sensor to 27 N.m (20 lb ft).
13. Connect the FTP sensor connector (1).
14. Connect the HPL solenoid connectors (5, 7).
15. Ensure that the HPL line fittings and the fuel lines are properly oriented. On ZW9 vehicles the FTP sensor should be at the 12 O'clock position.
16. Loosen the tank strap bolts and rotate the tank as required in order to align the fuel line and fittings. Tighten: Tighten the tank strap mounting bolts to 47 N.m (35 lb ft).
17. Connect the tee fitting (3) to the HPL fitting (2) with a new O-ring face seal. Lubricate the O-ring face seal with petroleum jelly. On ZW9 vehicles connect the fuel outlet line to the fitting. Tighten: Tighten the line fitting to 37 N.m (27 lb ft).
18. Connect the fuel line fitting (4) to the tee fitting with a new O-ring face seal. Lubricate the O-ring face seal with petroleum jelly. On ZW9 vehicles connect the fuel inlet line to the fitting. Tighten: Tighten the line fitting to 37 N.m (27 lb ft).
19. On ZW9 vehicles proceed directly to Step 30.
20. Slide the lower tank cover mounting bracket over the HPR and into position.
21. Install the lower tank cover mounting bracket and bolts (2). Tighten: Tighten the bolts to 50 N.m (37 lb ft).
22. Attach the HPR coolant hoses to the lower tank cover mounting bracket retainers.
23. Install the HPR mounting nut (1). Tighten: Tighten the nut to 54 N.m (40 lb ft).
24. Install the filter spring (4), filter (3) and seal (2) into the HPR inlet port.
25. Install the HPR fuel inlet line fitting (6) with a new O-ring. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line fitting to 48 N.m (35 lb ft).
26. Install the fuel filter and line assembly. Tighten: Tighten the bolts (1) to 27 N.m (20 lb ft).
27. Fasten the fuel line at the lower tank cover mounting bracket (4) and the tank strap (3).
28. Connect the HPR fuel inlet line (3) with a new O-ring face seal. Lubricate the O-ring face seal using petroleum jelly. Tighten: Tighten the fitting to 37 N.m (27 lb ft).
29. Install the upper tank cover mounting bracket (1). Tighten: Tighten the bolts to 8 N.m (71 lb in).
30. Ensure that the HPL manual shut-off valve is open by turning the Allen screw valve counterclockwise until fully seated.
31. Fill the tank and using the J 45878 inspect the HPL O-ring for leaks at each of the following pressures. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) . 3447 kPa (500 psi) 10,342 kPa (1,500 psi) 20,684 kPa (3,000 psi)
32. Connect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.
33. Prime the CNG fuel system by cycling the ignition ON and OFF several times.
34. Start the engine and use the J 45878 in order to inspect for CNG fuel system leaks at each serviced fitting. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
35. Install the fuel tank cover. Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) . Install the truck body or side panel as required on ZW9 equipped vehicles.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Disconnect the low pressure lock-off (LPL) solenoid electrical connector (5).
4. Disconnect the fuel inlet line (1) from the LPL fitting (2).
5. Remove the intermediate pressure regulator (IPR) fuel outlet line hold-down nut (6).
6. Remove the fuel outlet line hold down (4).
7. Disconnect the IPR fuel outlet lines (5, 8) from the IPR (2).
8. Remove the IPR/LPL bracket nuts (3).
9. Remove the IPR/LPL assembly from the vehicle.
10. Remove the bolts (3) that retain the IPR/LPL assembly (1, 4) to the bracket (2).
11. While holding the line union (2) rotate and remove the IPR (3) or the LPL (1) as required.

1. While holding the line union (2) rotate and install the IPR (3) or the LPL (1) as required. Tighten: Tighten the IPR or LPL hand tight plus one to three turns as required to align the IPR/LPL assembly to the bracket.
2. Install the IPR/LPL assembly (1, 4) to the mounting plate (2) using the attaching bolts (3). Tighten: Tighten the bolts to 12 N.m (9 lb ft).
3. Install the IPR/LPL bracket (4) to the engine (2) using the attaching nuts (3). Tighten: Tighten the nuts to 12 N.m (9 lb ft).
4. Connect the IPR fuel outlet lines (5, 8) to the IPR (2) using new O-rings (3). Lubricate the O-ring with petroleum jelly.
5. Install the line hold-down bracket (4) and nut (6). Tighten: Tighten the nut to 9 N.m (80 lb in).
6. Connect the LPL electrical connector (5). Connect the fuel inlet line (1) to the LPL fitting (2) using a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fitting to 37 N.m (27 lb ft).
7. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
8. Start the vehicle and inspect for CNG fuel leaks at the serviced fitting using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Disconnect the low pressure lock-off (LPL) solenoid electrical connector (5).
4. Disconnect the fuel inlet line (1) from the LPL fitting (2).
5. Remove the intermediate pressure regulator (IPR) fuel outlet line hold-down nut (6).
6. Remove the fuel outlet line hold down (4).
7. Disconnect the IPR fuel outlet lines (5, 8) from the IPR (2).
8. Remove the IPR/LPL bracket nuts (3).
9. Remove the IPR/LPL assembly from the vehicle.
10. Remove the bolts (3) that retain the IPR/LPL assembly (1, 4) to the bracket (2).
11. While holding the line union (2) rotate and remove the IPR (3) or the LPL (1) as required.

1. While holding the line union (2) rotate and install the IPR (3) or the LPL (1) as required. Tighten: Tighten the IPR or LPL hand tight plus 1-3 turns as required to align the IPR/LPL assembly to the bracket.
2. Install the IPR/LPL assembly (1, 4) to the mounting plate (2) using the attaching bolts (3). Tighten: Tighten the bolts to 12 N.m (9 lb ft).
3. Install the IPR/LPL bracket (4) to the engine (2) using the attaching nuts (3). Tighten: Tighten the nuts to 12 N.m (9 lb ft).
4. Connect the IPR fuel outlet lines (5, 8) to the IPR (2) using new O-rings (3). Lubricate the O-ring with petroleum jelly.
5. Install the line hold-down bracket (4) and nut (6). Tighten: Tighten the nut to 9 N.m (80 lb in).
6. Connect the LPL electrical connector (5). Connect the fuel inlet line (1) to the LPL fitting (2) using a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fitting to 37 N.m (27 lb ft).
7. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
8. Start the vehicle and inspect for CNG fuel leaks at the serviced fitting using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .

1. Relieve the CNG fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Relieve the gasoline fuel system pressure. Refer to Fuel Pressure Relief Procedure in Engine Controls in the C/K Pickup service manual.
3. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
4. Before removal, clean the fuel rail assemblies with a spray type engine cleaner, GM X-30A or equivalent, if necessary. Follow the package instructions. Do not soak fuel rails in liquid cleaning solvent.
5. Remove the engine sight shield. Refer to Engine Sight Shield Replacement (4.8L, 5.3L, and 6.0L Engines) Engine Sight Shield Replacement (6.0L Engine w/RPOs Y91 and Z88) in Engine Mechanical in the C/K Pickup service manual.
6. Loosen and remove the fuel line to rail clamps (9).
7. Remove the fuel line retainers (7).
8. Disconnect the fuel lines (5, 8) from the fuel rails (1, 10).
9. Disconnect the fuel rail temperature and pressure sensor electrical connectors (7, 2).
10. Disconnect the 8 CNG fuel injector electrical connectors (6).
11. Disconnect the accelerator control cable and the cruise control cable from the cable bracket (if equipped).
12. Disconnect the accelerator control cable and the cruise control cable from the throttle body (if equipped).
13. Remove the upper engine wire harness retainer nut.
14. Disconnect the evaporative emission (EVAP) purge valve harness connector.
15. Reposition the upper engine wire harness aside.
16. Pull the top portion (2) of the injector connector up. Do not pull the top portion of the connector past the top of the white portion (1).
17. Push the tab (1) on the lower side of the injector connector in order to release the connector from the injector.
18. Repeat Step 16 and Step 17 for each gasoline injector connector.
19. Disconnect the fuel feed and return pipes (1, 2) from the fuel rail.
20. Disconnect the fuel pressure regulator vacuum line.
21. Loosen the crossover tube (3) to right fuel rail retainer screw.
22. Remove the left fuel rail attaching bolts (3, 4).
23. Remove the right fuel rail attaching bolts (3).
24. Remove the gasoline and CNG fuel rails (1, 8, 4, 5) as an assembly.

1. Install the fuel rail assembly into the intake manifold.
2. Apply a 5 mm (0.020 in) band of GM P/N 1234382 threadlock, or equivalent, to the threads of all of the fuel rail attaching bolts.
3. Install the right fuel rail attaching bolts (3). Tighten: Tighten the bolts to 10 N.m (89 lb in).
4. Install the left fuel rail attaching bolts (3, 4). Tighten: Tighten the bolts to 10 N.m (89 lb in).
5. Tighten the gasoline crossover pipe retainer. Tighten: Tighten the screws to 3.8 N.m (34 lb in).
6. Connect the fuel injector electrical connectors to the corresponding engine cylinder injector for both gasoline and CNG.
7. Connect the CNG fuel rail pressure sensor and temperature sensor electrical connectors.
8. Connect the fuel pressure regulator vacuum line.
9. Connect the gasoline fuel feed and return pipes (1, 2) to the fuel rail.
10. Install the CNG fuel lines (5, 8) into the fuel rails (1, 10) with new O-rings. Lubricate the O-rings with petroleum jelly.
11. Install the fuel line to rail retainers (7) and clamps (9). Tighten: Tighten the clamps to 2 N.m (18 lb in).
12. Position the upper engine wire harness in place.
13. Connect the EVAP purge solenoid connector.
14. Install the retainer nut to the upper engine wire harness. Tighten: Tighten the nut to 5.5 N.m (49 lb in).
15. Connect the accelerator control cable and the cruise control cable to the throttle body (if equipped).
16. Connect the accelerator control cable and the cruise control cable to the cable bracket (if equipped).
17. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
18. Start the vehicle and inspect for CNG fuel leaks at the serviced fittings with the J 45878 or an equivalent leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
19. With a scan tool command a switch-over to gasoline and inspect for gasoline fuel leaks.
20. Install the engine sight shield. Refer to Engine Sight Shield Replacement (4.8L, 5.3L, and 6.0L Engines) Engine Sight Shield Replacement (6.0L Engine w/RPOs Y91 and Z88) in Engine Mechanical in the C/K Pickup service manual.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Before removal, clean the fuel rail assembly with a spray type engine cleaner, GM X-30A or equivalent, if necessary. Follow the package instructions. Do not soak fuel rails in liquid cleaning solvent.
4. Remove the engine sight shield. Refer to Engine Sight Shield Replacement (4.8L, 5.3L, and 6.0L Engines) Engine Sight Shield Replacement (6.0L Engine w/RPOs Y91 and Z88) in Engine Mechanical in the C/K Pickup service manual.
5. Loosen and remove the fuel line to rail clamps (9).
6. Remove the fuel line retainers (7).
7. Disconnect the fuel lines (5, 8) from the fuel rails (1, 10).
8. Disconnect the fuel rail temperature and pressure sensor electrical connectors (7, 2).
9. Disconnect the 8 fuel injector electrical connectors (6).
10. Remove the fuel rail attaching bolts (1).
11. Remove the fuel rail with injectors as an assembly.

1. Install the fuel rails (3, 4) into the intake manifold.
2. Apply a 5 mm (0.020 in) band of GM P/N 1234382 threadlock, or equivalent, to the threads of the fuel rail attaching bolts.
3. Install the fuel rail attaching bolts (1). Tighten: Tighten the bolts to 10 N.m (89 lb in).
4. Connect the fuel injector electrical connectors (6) to the corresponding engine cylinder injector.
5. Connect the fuel rail pressure and temperature sensor electrical connectors (2, 7).
6. Install the fuel lines (5, 8) into the fuel rails (1, 10) using new O-rings. Lubricate the O-rings with petroleum jelly.
7. Install the fuel line to rail retainers (7) and clamps (9). Tighten: Tighten the clamps to 2 N.m (18 lb in).
8. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
9. Start the vehicle and inspect for CNG fuel leaks at the serviced fittings using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
10. Install the engine sight shield (2). Refer to Engine Sight Shield Replacement (4.8L, 5.3L, and 6.0L Engines) Engine Sight Shield Replacement (6.0L Engine w/RPOs Y91 and Z88) in Engine Mechanical in the C/K Pickup service manual.

1. Remove the fuel rail assembly. Refer to «Fuel Rail Assembly Replacement (KL6)»(ref-184498-S22825064072005082300000) or «Fuel Rail Assembly Replacement (KL8)»(ref-184498-S09293353042005082300000) .
2. Remove the injector (5) hold down clip.
3. Remove the injector from the fuel rail with a pulling a twisting motion.
4. Repeat steps 2 and 3 for the remaining fuel injectors.

1. Install the fuel injector (5) into the fuel rail (3, 4) using a new O-ring. Lubricate the new O-ring with petroleum jelly.
2. Install the fuel injector retainer clip.
3. Lubricate the new injector tip O-ring with clean engine oil.
4. Repeat steps 1, 2 and 3 for the remaining fuel injectors.
5. Install the fuel rail assembly. Refer to «Fuel Rail Assembly Replacement (KL6)»(ref-184498-S22825064072005082300000) or «Fuel Rail Assembly Replacement (KL8)»(ref-184498-S09293353042005082300000) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Remove the engine sight shield.
4. Disconnect the sensor connector.
5. Support the fuel rail flange (4) with a back-up wrench (3) while loosening the sensor (2) with a wrench (1).
6. Remove the sensor (2) from the fuel rail.
7. Remove and discard the O-rings.

1. Install the sensor (2) into the fuel rail (4) with a new O-ring. Lubricate the O-ring with petroleum jelly.
2. Support the fuel rail flange (4) with a back-up wrench (3) while tightening the sensor (2) with a crowfoot and torque wrench. Tighten: Tighten the sensor to 9 N.m (80 lb in).
3. Connect the sensor electrical sensor.
4. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
5. Start the vehicle and inspect for CNG fuel leaks at the serviced fitting using the J 45878 or an equivalent leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
6. Install the engine sight shield.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Remove the engine sight shield.
4. Disconnect the sensor connector.
5. Support the fuel rail flange (4) with a back-up wrench (3) while loosening the sensor (2) with a wrench (1).
6. Remove the sensor (2) from the fuel rail.
7. Remove and discard the O-rings.

1. Install the sensor (2) into the fuel rail (4) with a new O-ring. Lubricate the O-ring with petroleum jelly.
2. Support the fuel rail flange (4) with a back-up wrench (3) while tightening the sensor (2) with a crowfoot and torque wrench. Tighten: Tighten the sensor to 9 N.m (80 lb in).
3. Connect the sensor electrical sensor.
4. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
5. Start the vehicle and inspect for CNG fuel leaks at the serviced fitting using the J 45878 or an equivalent leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
6. Install the engine sight shield.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.
3. Remove the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .
4. Disconnect the fill line (6) at the check valve fitting (5).
5. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information in the C/K Pickup Service Manual.
6. Disconnect the fill line (3) at the fill valve fitting (2).
7. Remove the fill line from the vehicle.

1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information in the C/K Pickup Service Manual.
2. Install the fill line into the vehicle.
3. Connect the fill line (3) to the fill valve (2) with a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fitting to 24 N.m (18 lb ft).
4. Lower the vehicle.
5. Connect the fill line (6) to the check valve fitting (5) with a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fitting to 24 N.m (18 lb ft).
6. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.
7. Start the vehicle and inspect for CNG fuel leaks at the serviced fittings using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
8. Install the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Remove the truck body as required on ZW9 equipped vehicles in order to gain access to the CNG fuel tank.
4. Disconnect the fill line (3) at the fill valve (1).
5. Disconnect the fill line (1) at the high pressure lock-off (HPL) solenoid.
6. Remove the fuel line retaining clips (1).
7. Remove the check valve mounting bolt (4).
8. Remove the fill line assembly from the vehicle.

1. Install the fill line into the vehicle.
2. Install the fuel line retaining clips (1).
3. Connect the fill line (3) to the fill valve (1) with a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fitting to 37 N.m (27 lb ft).
4. Connect the fill line (1) to the HPL with a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fitting to 37 N.m (27 lb ft).
5. Install the check valve mounting bolt (4). Tighten: Tighten the bolt to 12 N.m (9 lb ft).
6. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
7. Start the vehicle and inspect for CNG fuel leaks at the serviced fittings using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
8. Install the truck body as required on ZW9 equipped vehicles.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.
3. Remove the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .
4. Disconnect the line at the fuel filter outlet (2).
5. Disconnect the fuel line hold down clips (3).
6. Disconnect the fuel line (3) from the high pressure regulator (HPR) (1) inlet fitting.
7. Remove the line from the vehicle.

1. Install the line into the vehicle.
2. Connect the line (3) to the high pressure regulator (HPR) (1) inlet fitting using a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
3. Connect the fuel line to the fuel filter outlet fitting (2) using a new O-ring. Lubricate the O-ring face seal with petroleum jelly. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
4. Install the fuel line hold down clips (3).
5. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.
6. Start the vehicle and inspect for CNG fuel leaks at all serviced fittings using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
7. Install the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.
3. Remove the truck body as required on ZW9 equipped vehicles in order to gain access to the CNG fuel tank.
4. Disconnect the fuel filter inlet line (2).
5. Disconnect the high pressure regulator (HPR) fuel inlet line (3).
6. Remove the fuel filter mounting bolts (1).
7. Remove the fuel filter mounting bracket bolts (2, 4).
8. Remove the fuel filter/line assembly from the vehicle.
9. Observe and record the orientation of the fuel line.
10. Disconnect the fuel filter outlet line from the fuel filter.
11. Remove the fuel line from the filter mounting bracket assembly.

1. Install the fuel line through the hole in the filter mounting bracket.
2. Connect the line to the filter outlet fitting with a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
3. Install the fuel filter mounting bolts (1). Tighten: Tighten the bolts to 20 N.m (15 lb ft).
4. Install the fuel filter bracket mounting bolts (2, 4). Tighten: Tighten the bolts to 12 N.m (9 lb ft).
5. Connect the fuel line to the fuel filter inlet fitting (2) with a new O-ring. Lubricate the O-ring face seal with petroleum jelly. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
6. Connect the fuel line to the HPR inlet fitting (3) with a new O-ring. Lubricate the O-ring face seal with petroleum jelly. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
7. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup Service Manual.
8. Start the vehicle and inspect for CNG fuel leaks at all serviced fittings using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
9. Install the truck body as required on ZW9 equipped vehicles.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Remove the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .
4. Disconnect the fuel outlet line (4) at the HPL tee fitting (3).
5. Disconnect the line at the fuel filter inlet (5).
6. Disconnect the fuel line hold down clips (3, 4).
7. Remove the line from the vehicle.

1. Install the line into the vehicle.
2. Connect the line to the fuel filter inlet fitting (5) using a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
3. Connect the fuel outlet line (4) to the HPL tee fitting (3) with a new O-ring face seal. Lubricate the O-ring face seal with petroleum jelly. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
4. Install the fuel line hold down clips (3, 4).
5. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
6. Start the vehicle and inspect for CNG fuel leaks at all serviced fittings using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
7. Install the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000)

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Remove the truck body as required on ZW9 equipped vehicles in order to gain access to the CNG fuel tank.
4. Disconnect the fuel filter inlet line (2).
5. Remove the fuel line retainer clips (1).
6. Disconnect the fuel outlet line (3) at the high pressure lock-off (HPL).
7. Remove the line from the vehicle.

1. Install the line into the vehicle.
2. Connect the line (3) to the HPL outlet fitting with a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fitting to 37 N.m (27 lb ft).
3. Connect the line to the filter inlet (2) with a new O-ring face seal. Lubricate the O-ring face seal with petroleum jelly. Tighten: Tighten the fitting to 37 N.m (27 lb ft).
4. Install the fuel line retainer clips (1).
5. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
6. Start the vehicle and inspect for CNG fuel leaks at all serviced fittings using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
7. Install the truck body as required on ZW9 equipped vehicles.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Remove the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .
4. Disconnect the fill line (6) from the check valve (5).
5. Disconnect the check valve (5) from the tee (3).
6. Remove the fill line check valve from the vehicle.

1. Connect the fuel fill line check valve (5) to the HPL tee fitting (3) with a new O-ring face seal. Lubricate the O-ring face seal with petroleum jelly. Tighten: Tighten the fitting to 24 N.m (18 lb ft).
2. Connect the fuel fill line (6) to the check valve (5) with a new O-ring face seal. Lubricate the O-ring face seal with petroleum jelly. Tighten: Tighten the fitting to 24 N.m (18 lb ft).
3. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
4. Start the vehicle and inspect for CNG fuel leaks at the serviced fittings using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
5. Install the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Remove the truck body as required on ZW9 equipped vehicles in order to gain access to the CNG fuel tank.
4. Disconnect the fuel fill hose from the check valve (4).
5. Disconnect the fuel fill line from the check valve (4).
6. Remove the check valve mounting bolt (4).
7. Remove the check valve from the vehicle.

1. Connect the fuel fill line to the check valve (4) with a new O-ring face seal. Lubricate the O-ring face seal with petroleum jelly. Tighten: Tighten the fitting to 37 N.m (27 lb ft).
2. Connect the fuel fill hose to the check valve (4) with a new O-ring face seal. Lubricate the O-ring face seal with petroleum jelly. Tighten: Tighten the fitting to 37 N.m (27 lb ft).
3. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
4. Start the vehicle and inspect for CNG fuel leaks at the serviced fittings using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
5. Install the truck body as required on ZW9 equipped vehicles.

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information in the C/K Pickup service manual.
4. Disconnect the center fuel line (5) from the low pressure lock-off (LPL) solenoid fuel line (2).
5. Lower the vehicle.
6. Disconnect the LPL fuel line (1) from the LPL solenoid fitting (2).
7. Remove the line from the vehicle.

1. Install the fuel line (1) into the vehicle.
2. Connect the fuel line (1) to the low pressure lock-off (LPL) solenoid fitting (2) using a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
3. Connect the center fuel line (5) to the LPL fuel line (2) using a new O-ring. Lubricate the O-ring face seal with petroleum jelly. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
4. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
5. Start the vehicle and inspect for CNG fuel leaks at the serviced fitting using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Remove the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .
4. Disconnect the HPR fuel outlet line (4).
5. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information in the C/K Pickup service manual.
6. Disconnect the HPR fuel outlet line (3).
7. Remove the line from the vehicle.

1. Install the line (3) into the vehicle.
2. Connect the high pressure regulator (HPR) line (3) to the underbody line (2) using a new O-ring face seal. Lubricate the O-ring with petroleum jelly. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
3. Connect the fuel line (4) to the HPR fitting (3) using a new O-ring. Lubricate the O-ring face seal with petroleum jelly. Tighten: Tighten the fuel line to 37 N.m (27 lb ft).
4. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
5. Start the vehicle and inspect for CNG fuel leaks at the serviced fitting using the J 45878 or an equivalent liquid leak detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .
6. Install the tank cover (2). Refer to «Fuel Tank Cover Replacement»(ref-184498-S06677910822005082300000) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Remove the intermediate pressure regulator (IPR) fuel outlet line hold-down nut (6).
4. Remove the fuel outlet line hold down (4).
5. Disconnect the IPR fuel outlet lines (5, 8) from the IPR (2).
6. Loosen the IPR fuel outlet line screw clamp (9) at the fuel rail.
7. Remove the IPR fuel outlet line hold downs (7) at the fuel rail.
8. Remove the IPR fuel outlet line from the vehicle.

1. Connect the IPR fuel outlet lines (5, 8) to the IPR (2) using new O-rings (3). Lubricate the O-ring with petroleum jelly.
2. Install the line hold-down bracket (4) and nut (6). Tighten: Tighten the nut to 9 N.m (80 lb in).
3. Connect the IPR fuel outlet line at the fuel rail using the hold downs (7).
4. Assemble the IPR fuel outlet line screw clamp (9) around the hold downs (7). Tighten: Tighten the screw clamp to 2 N.m (18 lb in).
5. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
6. Start the vehicle and inspect for CNG fuel leaks at the serviced fitting using the J 45878 or an equivalent combustible gas detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .

1. Relieve the fuel system pressure. Refer to «Fuel Pressure Relief Procedure»(ref-184498-S35460101902005082300000) .
2. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
3. Remove the intermediate pressure regulator (IPR) fuel outlet line hold-down nut (6).
4. Remove the fuel outlet line hold down (4).
5. Disconnect the IPR fuel outlet lines (5, 8) from the IPR (2).
6. Loosen the IPR fuel outlet line screw clamp (9) at the fuel rail.
7. Remove the IPR fuel outlet line hold downs (7) at the fuel rail.
8. Remove the IPR fuel outlet line from the vehicle.

1. Connect the IPR fuel outlet lines (5, 8) to the IPR (2) using new O-rings (3). Lubricate the O-ring with petroleum jelly.
2. Install the line hold-down bracket (4) and nut (6). Tighten: Tighten the nut to 9 N.m (80 lb in).
3. Connect the IPR fuel outlet line at the fuel rail using the hold downs (7).
4. Assemble the IPR fuel outlet line screw clamp (9) around the hold downs (7). Tighten: Tighten the screw clamp to 2 N.m (18 lb in).
5. Install the negative battery cable. Refer to Battery Negative Cable Disconnect/Connect Procedure (Single Battery) Battery Negative Cable Disconnect/Connect Procedure (Auxiliary Battery) in Engine Electrical in the C/K Pickup service manual.
6. Start the vehicle and inspect for CNG fuel leaks at the serviced fitting using the J 45878 or an equivalent combustible gas detector. See «Special Tools and Equipment»(ref-184498-S25171947842005082300000) .