Engine Controls - Basic Diagnostic Procedures - 6.6L Diesel: Diagnosis Chevrolet Silverado 1500 HD

VISUAL INSPECTION

Visually inspect all electrical wiring. Look for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and not pinched or cut. If necessary, see VACUUM DIAGRAMS in VACUUM DIAGRAMS - SIERRA & SILVERADO article to verify routing and connections. Inspect air induction system for possible vacuum leaks.

NO-START DIAGNOSIS

Note. For terminal and circuit identification, see WIRING DIAGRAMS .

1. Definition - No-start is defined as engine cranks properly, but does not start. Engine may fire a few times.

Scheme 11

Scheme 12

Scheme 13

Diagnostic Aids

If the cause of an engine cranks but will not run condition has not been found, inspect for the following conditions

1. Hard starting only in cold ambient temperatures.
2. The correct cranking speed is 100 RPM cold and 180 RPM hot. A scan tool can be used to inspect cranking speed by pulling the ignition 1 relay and monitoring engine speed on scan tool while cranking.
3. Water or foreign material in fuel system.
4. A basic engine problem.
5. If CKP sensor and CMP sensor are disconnected or malfunctioning at the same time, an engine cranks but does not run condition will exist.

FUEL SYSTEM DIAGNOSIS - HIGH PRESSURE SIDE

Note. Do not perform this procedure if you were not referred to this test from another diagnostic. Perform this test only when fuel is more than 65°F (18°C). All of the fuel return volumes are based on No. 2 diesel fuel. A vehicle with No. 1 diesel fuel will have higher values.

1. Were you referred here from another diagnostics? If yes, perform Fuel Pressure Regulator Graphing. Refer to Tech 2 scan tool instructions. If no, go to next step.
2. Remove air duct from air cleaner assembly and turbo inlet.
3. Remove air intake pipe.
4. Remove fuel injection pump fuel return hose from the junction block. see scheme 4 Cap the fitting on the block with a 3/8" rubber cap to prevent fuel leakage.
5. Attach a rubber hose with a barbed fitting to the fuel injection pump return hose and insert the other end into a one gallon clean fuel container.
6. Remove ignition 1 relay. Relay is located in underhood fuse/relay block.
7. Remove glow plug controller/relay. Relay is located in underhood fuse/relay block.
8. Remove fuel line retainers.
9. Remove banjo bolt from left rear cylinder head.
10. Install the Black hose from the Graduated Cylinders Kit (J-45873) to the left rear cylinder head and install the other end of the hose into one of the graduated cylinders.
11. Remove banjo bolt from the leak-off block.
12. Install the other Black hose from the kit to the leak-off block and install the other end of the hose into another graduated cylinder.
13. Remove banjo bolt from the fuel junction block. Fuel junction block is located under A/C compressor.
14. Crank engine for 15 seconds while observing the fuel pressure relief valve on the junction block for fuel leakage. If fuel is leaking from the fuel pressure relief valve, replace the fuel pressure relief valve. If no fuel is leaking from the fuel pressure relief valve, go to next step.
15. Crank engine in 15 second intervals, with one minute cooling time between, until fuel starts to flow into one or both of the graduated cylinders.
16. Elevate the hoses to retain fuel in the hoses and empty the graduated cylinders into a suitable container.
17. Install the hoses into 2 of the graduated cylinders.
18. Crank engine for 15 seconds. The engine cranking speed must be more than 150 RPM.
19. Measure the quantity of fuel in each of the graduated cylinders. If there is more than 12 ml of fuel from either cylinder bank, remove the valve cover from that bank, then go to next step. If there is less than 12 ml from each cylinder bank, replace the fuel injection pump and repeat steps 15 - 19. If fuel injection pump has already been replaced in this repair and there is less than 12 ml of fuel from each bank, go to step 40.
20. Remove return line from injectors.
21. Install the 4 Yellow hoses from the kit to the injectors and place the other end of the hoses into each of the graduated cylinders.
22. Install all 4 injector supply lines. Tighten supply lines to 32 ft. lbs. (44 N.m).
23. Connect the engine-to-chassis harness connectors to enable the starter.
24. Install fuel supply hose. Push hose in until it locks.
25. Install Black hoses from the kit into the same container that the fuel injection pump return hose is in. Prime fuel system 30 times to remove air from fuel system. Air will be forced out of the system within 2 minutes.
26. Crank engine in 15 second intervals, with one minute cooling time between, until fuel starts to flow into one or more of the graduated cylinders.
27. Elevate the 4 hoses to retain fuel in hoses, and empty the 4 graduated cylinders into a suitable container.
28. Install hoses in the graduated cylinders in numerical order.
29. Crank engine for 15 seconds. The engine cranking speed must be more than 150 RPM.
30. Measure the quantity of fuel in each of the graduated cylinders. If there is more than 3 ml of fuel flow from any fuel injector(s), replace the high flowing fuel injector(s). After replacing injector(s), go to step 32. If no fuel injector has a flow of more than 3 ml, install the valve cover. After installing the valve covers, go to step 32.
31. Repeat steps 25 - 30 until no fuel injectors have more than 3 ml of fuel flow.
32. Were both banks of fuel injectors tested with steps 25 - 32? If yes, go to step 41. If no, go to next step.
33. Reassemble fuel return line and valve cover.
34. Ensure that hoses are still installed as they were in steps 10 - 13.
35. Prime the fuel system 30 times to remove the air from the fuel system. See «FUEL SYSTEM PRIMING»(ref-152810-S36449314872003051900000). Air will be forced out of the system within 2 minutes.
36. Crank engine in 15 second intervals, with one minute cooling time between, until fuel starts to flow into one or both of the graduated cylinders.
37. Elevate the hoses to retain fuel in the hoses and empty the graduated cylinders into a suitable container.
38. Install the hoses into 2 of the graduated cylinders.
39. Crank engine for 15 seconds while observing the fuel pressure relief valve for fuel leaks. Engine cranking speed must be more than 150 RPM. If relief valve leaks, replace relief valve and repeat steps 36 - 39.
40. Measure the quantity of fuel in each of the graduated cylinders. If there is more than 12 ml of fuel in either of the 2 cylinders, perform steps 25 - 31 on the bank of fuel injectors with the high fuel flow, then go to next step. If both of the cylinder have less than 12 ml of fuel, go to next step.
41. Install all disconnected and removed components.
42. Start and operate engine at idle. You may have to prime the fuel system before the engine will start.
43. Connect scan tool.
44. Command fuel pressure control to 160 MPa with scan tool. If the fuel pressure is more than 145 MPa, system is okay. If fuel pressure is unable to increase to more than 145 MPa, replace fuel injection pump.