Engine Control System - Basic Diagnostic Procedures: Diagnosis Oldsmobile Aurora II

VISUAL INSPECTION

Visually inspect all electrical wiring, looking 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 appropriate VACUUM DIAGRAMS article to verify routing and connections. Inspect air induction system for possible vacuum leaks.

Diagnosis

1. Start engine and allow it to reach normal operating temperature. Increase engine speed to 2000-2500 RPM and note gauge. If reading exceeds 1.25 psi (.09 kg/cm 2 ), exhaust system is restricted.
2. Check exhaust system for collapsed pipe, heat distress and possible internal muffler failure. If none of these conditions exist, check for restricted catalytic converter. Replace as necessary.

NO-START DIAGNOSIS

Note. Some vehicles are equipped with anti-theft systems (VATS or PASS-Key®) which will not allow vehicle to be started if improper starting procedures or improperly coded ignition keys are used. Both fuel injection and cranking systems will be disabled. Loss of fuel enable signal from anti-theft decoder module should set a diagnostic trouble code in PCM memory.

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

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

General Inspection

1. Using scan tool, attempt communication with BCM and PCM. If communication can be established, go to next step. If communication cannot be established, diagnose communication problem. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
2. If BCM or PCM Passlock®/security system or BCM communication DTCs (P1630, P1631, U1000, U1064, U1300 or U1301) are set, diagnose these DTCs first. See appropriate SELF-DIAGNOSTICS article or appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If listed DTCs are not set, go to next step.
3. Using scan tool, monitor IGNITION 1 voltage. If voltage is 2 volts or greater, go to next step. If voltage is not 2 volts or greater, check PCM ignition feed circuit or PCM ground circuits for an open or poor connection. Repair as necessary.
4. If any PCM internal fault DTCs (P0601, P0602, P0603, P0606 or P1621) are set, diagnose these DTCs first. See appropriate SELF-DIAGNOSTICS article. If listed DTCs are not set, go to next step.
5. If all 4 injector circuit low DTCs (P0261, P0264, P0267 or P0270) are set, repair ignition voltage circuits between underhood junction block and fuel injectors. Check INJ fuse (10-amp) in underhood junction block. Replace if necessary. If listed DTCs are not set, go to next step.
6. If any ignition control DTCs (P0351, P0352, P1351 or P1352) are set, diagnose these DTCs first. See appropriate SELF-DIAGNOSTICS article. If listed DTCs are not set, go to next step.
7. If DTC P1635 is set, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If listed DTC is not set, go to next step.
8. If DTCs P0231 or P0232 are set, diagnose these DTCs first. See appropriate SELF-DIAGNOSTICS article. If listed DTCs are not set, go to next step.
9. Using scan tool, monitor EGR sensor. If voltage is less than one volt, go to next step. If voltage is not less than one volt, perform diagnostic procedure for DTC P1404. See appropriate SELF-DIAGNOSTICS article.
10. Using scan tool, monitor CMP resync counter while cranking engine. If counter increments, go to next step. If counter does not increment, see «NO RPM DETECTED DIAGNOSIS»(ref-129078-S33665507202001111200000) .
11. Check for spark at plug wires No. 2 and 4. If spark is present at both plug wires, go to next step. If spark is not present at both plug wires, see «IGNITION DIAGNOSIS»(ref-129078-S18119378972001111200000) .
12. Check for fouled spark plugs. Repair as necessary. If spark plugs are okay, see «FUEL DELIVERY DIAGNOSIS»(ref-129078-S31560484332001111200000) .

No RPM Detected Diagnosis

1. Turn ignition off. Disconnect 80-pin PCM harness connector. Measure resistance between 7X signal high circuit and 7X signal low circuit at PCM harness connector. If resistance is 800-1600 ohms, go to next step. If resistance is less than 800 ohms, go to step 3 . If resistance is greater than 1600 ohms, go to step 4 .
2. Check CKP sensor for correct torque and terminal tension. Repair as necessary. If CKP sensor and connections are okay, replace PCM. Perform PCM relearn procedure.
3. Disconnect CKP sensor. Check for continuity between 7X signal high circuit and 7X signal low circuit at CKP sensor harness connector. If continuity is present, repair circuits for short together. If continuity is not present, replace CKP sensor.
4. Disconnect CKP sensor. Check for open in 7X signal high circuit or 7X signal low circuit. Repair as necessary. If circuits are okay, CKP sensor or connections are faulty.

Ignition Diagnosis

Note. If DTCs P0351, P0352, P1351 or P1352 are set, diagnose these DTCs first. See appropriate SELF-DIAGNOSTICS article.

1. Check for spark at all spark plug wires. If spark is not present on only one wire, replace faulty wire. If spark is not present on 2 wires sharing the same ignition coil, replace faulty ignition coil. If spark is not present at any wire, go to next step.
2. Check EIS fuse (10-amp) located in underhood fuse block. Replace if necessary. Turn ignition on. Disconnect EI module harness connector. Using test light connected to ground, probe ignition feed circuit at EI module harness connector. If test light illuminates, go to next step. If test light does not illuminate, repair open in ignition feed circuit.
3. Using test light connected to battery positive terminal, probe ground circuit at EI module harness connector. If test light illuminates, EI module or connections are faulty. If test light does not illuminate, repair open in ground circuit.

Fuel Delivery Diagnosis

1. Install fuel pressure gauge. See «BASIC FUEL SYSTEM CHECKS»(ref-129078-S17359572062001111200000) . Using scan tool, command fuel pump relay on and off for 3 pulses. If fuel pressure is 40-55 psi (2.8-3.9 kg/cm 2 ), fuel quality may be at fault. If fuel pressure is not as specified, go to next step.
2. If fuel pressure is not present, go to next step. If fuel pressure is present but not to specification, diagnose fuel system. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary.
3. Turn ignition off for at least 10 seconds. Using test light connected to ground, probe FUEL PUMP fuse (10-amp) located in instrument panel fuse block. Turn ignition on. If test light illuminates for 2 seconds and then turns off, go to next step. If test light does not illuminate, go to step 5 .
4. Check fuel pump battery feed circuit and fuel pump relay ground circuit for open or poor connections. Repair as necessary. If circuits are okay, fuel pump is faulty.
5. Using scan tool, command fuel pump relay on and off. If relay does not click, replace relay. If relay clicks, check I/P BATT fuse (30-amp) located in underhood fuse block. Replace if necessary. If fuse is okay, repair open in fuel pump relay battery feed circuit.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check ignition wires for cracking, hardness and proper connections.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

Diagnostic Aids

A small amount of resistance in battery feed circuit to PCM may cause a no-start condition. Test battery feed circuit for excessive resistance or corrosion. The PCM grounds will cause a no-start condition only if all are not making good connections. Inspect TP sensor for the following conditions

1. Binding
2. Sticking
3. Intermittent Short
4. Intermittent Open

Refer to DTC P0105 for testing. See appropriate SELF-DIAGNOSTICS article.

The ECT sensor may be skewed within specifications and may not set a DTC. On a cold vehicle, ECT and IAT values should be within 5°F of each other. On a hot vehicle, let engine cool to ambient temperature, and then test ECT.

The MAP sensor may be skewed within specifications and not set a DTC. Refer to DTC P0105 for testing. See appropriate SELF-DIAGNOSTICS article. If CKP sensor is loose, it may cause an intermittent no-start condition by moving away from the reluctor wheel. Ensure sensor and matting surfaces are clean and tight.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
2. If any BCM communication or Passlock® DTCs (P1630, P1631, P1632, P1626 or U1064) are set, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article, or appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If listed DTCs are not set, go to next step.
3. Using scan tool, monitor ignition voltage. If voltage is less than 2 volts, see «PCM INPUT CIRCUITS»(ref-129078-S03786861452001111200000) . If voltage is not less than 2 volts, go to next step.
4. If any PCM internal DTCs (P0601or P0602) are set, diagnose DTCs first. See appropriate SELF-DIAGNOSTICS article. If listed DTCs are not set, go to next step.
5. If all 4 injector DTCs (P0201, P0202, P0203 and P0204) are set, repair ignition voltage to injectors. Check INJECTOR fuse (10-amp) located in underhood fuse block. If listed DTCs are not set, go to next step.
6. If any sensor DTCs (P0107, P0108, P0122, P0123, P0530, P0452 or P0453) are set, diagnose these DTCs first. See appropriate SELF-DIAGNOSTICS article. If listed DTCs are not set, go to next step.
7. While cranking engine, monitor CKP active counter with scan tool. If counter increments, go to next step. If counter does not increment, see «IGNITION MODULE CIRCUITS»(ref-129078-S06976597912001111200000) .
8. Using scan tool, monitor CAL COMPRESSION OUTPUT. If any 1s are present, go to «FUEL SYSTEM CIRCUITS»(ref-129078-S42692735592001111200000) . If no 1s are present, go to «IGNITION COIL CIRCUITS»(ref-129078-S15624743662001111200000) .

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check spark plug boots for cracking, hardness and proper connections.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
2. Check all fuses in power distribution center located next to battery, and FUEL PUMP fuse (20-amp) located in instrument panel fuse block. If any fuses are open, go to step 12 . If all fuses are okay, go to next step.
3. Check ECM ground circuit and ground circuit from battery to body for loose connections, corrosion, high resistance or opens. Repair as necessary. After repairs, go to step 13 . If circuits are okay, go to next step.
4. Using scan tool, check for DTCs that may cause a no-start condition (theft deterrent, powertrain, engine electrical, etc.). Repair as necessary. If no DTCs are present, go to next step.
5. Using scan tool, monitor theft deterrent status. If status reads CORRECT CODE, go to next step. If status does not read CORRECT CODE, perform SYSTEM OPERATION CHECK. See appropriate DOOR LOCKS & ANTI-THEFT SYSTEMS article.
6. Using scan tool, review data list for MAF, TP, APP, ECT and IAT sensors. Compare sensor values to known-good values. If sensor values are normal, go to next step. If sensor values are not normal, diagnose using appropriate DTC diagnostic procedure applicable to faulty sensor. See appropriate SELF-DIAGNOSTICS article.
7. Turn ignition on. Using scan tool, command fuel pump on. If fuel pump runs, go to next step. If fuel pump does not run, see «FUEL PUMP ELECTRICAL CIRCUIT»(ref-129078-S26804528982001111200000) .
8. Turn ignition off. Install fuel pressure gauge. See «BASIC FUEL SYSTEM CHECKS»(ref-129078-S17359572062001111200000) . Using scan tool, command fuel pump on. If pressure is 40-46 psi (2.8-3.2 kg/cm 2 ), go to next step. If pressure is not as specified, diagnose fuel system. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article.
9. Check ignition system. See «IGNITION CIRCUIT»(ref-129078-S12105132742001111200000) . Repair as necessary. After repairs, go to step 13 . If ignition system is okay, go to next step.
10. Check for air leaks in air duct between MAF sensor and throttle body. Check MAF sensor operation by disconnecting sensor and operating engine. If disconnecting sensor corrects no-start condition, replace MAF sensor. After repairs, go to step 13 . If no problem is found, go to next step.
11. Check for fouled spark plugs and cause. Check for contaminated fuel, restricted exhaust system or engine mechanical problem. Repair as necessary. After repairs, go to step 13 . If no problem is found, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article.
12. Repair affected fuse related circuit for short to ground. After repairs, go to next step.
13. Using scan tool, clear DTCs. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to step 2 .
14. Allow engine to idle and reach normal operating temperature. Using scan tool, check for DTCs. If DTCs are set, diagnose DTCs. See appropriate SELF-DIAGNOSTICS article. If no DTCs are set, system is okay.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check spark plug boots for cracking, hardness and proper connections.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition on. Using scan tool, command fuel pump on and off. If fuel pump runs when commanded, go to next step. If fuel pump does not run when commanded, see «FUEL PUMP ELECTRICAL CIRCUIT»(ref-129078-S11329044032001111200000) .
3. Install fuel pressure gauge. See «BASIC FUEL SYSTEM CHECKS»(ref-129078-S17359572062001111200000) . Turn ignition on. If pressure is 52-59 psi (3.7-4.2 kg/cm 2 ), go to next step. If pressure is not as specified, diagnose fuel system. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article.
4. Disconnect CKP sensor harness connector. Using scan tool, monitor 3X CKP sensor parameter while cranking engine. If scan tool indicates 3X signal, go to next step. If scan tool does not indicate 3X signal, see «IGNITION SYSTEM»(ref-129078-S08459673002001111200000) .
5. Reconnect CKP sensor harness connector. Remove F/INJR fuse (15-amp) located in underhood accessory wiring junction block. Using spark tester, check for spark at each coil tower while cranking engine. If spark is present, go to step 7 . If spark is not present, see «IGNITION SYSTEM»(ref-129078-S08459673002001111200000) .
6. Reinstall F/INJR fuse. Disconnect fuel injector in-line harness connector. Connect Injector Load Tester (J 34730-380) and Harness Adapter (J 34730-410). Observe load tester while cranking engine. If LEDs flash for all cylinders, go to next step. If LEDs do not flash for all cylinders, test fuel injectors. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article.
7. Check for air intake or exhaust system leaks or restrictions. Check for engine mechanical problems. Repair as necessary. After repairs, perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. If no problems are found, go to step 2 .

To prevent mis-diagnosis, perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK under DIAGNOSTIC SYSTEM CHECKS in appropriate SELF-DIAGNOSTICS article. Unless engine enters clear flood mode at first indication of a flooding condition, a no-start condition may result. Be sure to check spark plugs for signs of fouling. Inspect for leaks in the intake air ducting between the mass air flow sensor and throttle body. If no problems are found after performing test steps, perform diagnosis for hard start condition. See appropriate TROUBLE SHOOTING - NO CODES article.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

1. Ensure proper starting procedure is being used. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information (VECI) label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs.
2. Remove spark plugs. Check and replace as necessary. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline.

FUEL SYSTEM PRESSURE TEST (EXCEPT AURORA & SATURN)

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
2. Turn ignition off. Turn A/C system off. On all models except 2.2L and 2.4L, connect Fuel Pressure Gauge (J-34730-1A) to fuel pressure fitting on fuel rail. On 2.2L and 2.4L, install Fuel Pressure Gauge (J-29658-D). This kit modifies fuel pressure gauge so it may be installed in fuel delivery line with quick-connect fittings. On all models, place fuel pressure gauge bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition to obtain highest fuel pressure possible. Observe fuel pressure with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE SPECIFICATIONS (EXCEPT SATURN)»(ref-129078-S11667363572001111200000) table. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to step 12 .
3. Fuel pressure may vary slightly when fuel pump stops. After fuel pump stops, fuel pressure should stabilize and remain constant. Note fuel pressure when fuel pump stops running. If fuel pressure decreases more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, go to step 10 . If fuel pressure does not decrease more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, go to next step.
4. Relieve fuel pressure until pressure is 10 psi (0.7 kg/cm 2 ). If fuel pressure decreases more than 2 psi (0.1 kg/cm 2 ) in 10 minutes, go to step 19 . If fuel pressure does not decrease more than 2 psi (0.1 kg/cm 2 ) in 10 minutes, go to next step.
5. If fuel pressure is suspected of decreasing during acceleration, cruise or hard cornering, go to next step. If fuel pressure is not suspected of decreasing during acceleration, cruise or hard cornering, go to step 8 .
6. Inspect in-line fuel filter and fuel feed pipe for restriction. Repair as necessary. After repairs, go to step 24 . If no restriction is found, go to next step.
7. Remove fuel sending unit assembly. Inspect fuel pump strainer for restriction and correct installation. Check fuel pump flex pipe for leaks, and ensure fuel pump is correct for application. Repair as necessary. After repairs, go to step 24 . If no problem is found, go to step 19 .
8. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition to obtain highest fuel pressure possible. Note fuel pressure. Start engine. Allow engine to idle until normal operating temperature is reached. If fuel pressure is less than previously noted pressure by 3-10 psi (0.2-0.7 kg/cm 2 ), check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article. If fuel pressure is greater than previously noted pressure by 3-10 psi (0.2-0.7 kg/cm 2 ), go to next step.
9. Disconnect vacuum hose from fuel pressure regulator. With engine idling, apply 12-14 in. Hg of vacuum to fuel pressure regulator. If fuel pressure decreases by 3-10 psi (0.2-0.7 kg/cm 2 ), go to step 20 . If fuel pressure does not decrease by 3-10 psi (0.2-0.7 kg/cm 2 ), go to step 21 .
10. Turn ignition off. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)»(ref-129078-S02634835662001111200000) . Disconnect fuel supply and return hoses at fuel rail. Install Fuel Pipe Shutoff Adapters (J 37287) between fuel hoses and fuel rail pipes. Open valve on fuel pipe shutoff adapters. Place bleed hose into container. Turn ignition on. Using scan tool, command fuel pump on. Bleed air out of fuel pressure gauge. Using scan tool, command fuel pump on and off. Close valve on fuel supply pipe shutoff adapter. Monitor fuel pressure for one minute. If fuel pressure remains constant, go to step 19 . If fuel pressure does not remain constant, go to next step.
11. Turn ignition off. Open valve on fuel supply pipe shutoff adapter. Turn ignition on. Using scan tool, command fuel pump on and off. Close valve on return pipe shutoff adapter. Monitor fuel pressure for one minute. If fuel pressure remains constant, go to step 21 . If fuel pressure does not remain constant, go to step 22 .
12. If fuel pressure is greater than specification, go to next step. See «FUEL PRESSURE SPECIFICATIONS (EXCEPT SATURN)»(ref-129078-S11667363572001111200000) table. If fuel pressure is less than specification, go to step 15 .
13. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)»(ref-129078-S02634835662001111200000) . Disconnect fuel return pipe from fuel rail. Attach flexible fuel hose to fuel rail return outlet passage. Place other end of flexible hose into container. Turn ignition off for about 10 seconds. Turn ignition on. Observe fuel pressure gauge with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE SPECIFICATIONS (EXCEPT SATURN)»(ref-129078-S11667363572001111200000) table. If fuel pressure is within specification, go to step 23 . If fuel pressure is not within specification, go to next step.
14. Inspect fuel rail outlet passage for restriction. Repair as necessary. After repairs, go to step 24 . If no restriction is found, go to step 21 .
15. If fuel pressure is greater than zero psi, go to next step. If fuel pressure is zero psi, go to step 17 .
16. Turn ignition off. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)»(ref-129078-S02634835662001111200000) . Disconnect fuel supply and return hoses at fuel rail. Install Fuel Pipe Shutoff Adapters (J 37287) between fuel hoses and fuel rail pipes. Open valve on fuel pipe shutoff adapters. Place bleed hose into container. Turn ignition on. Using scan tool, command fuel pump on. Bleed air out of fuel pressure gauge. DO NOT allow fuel pressure to exceed 65 psi. Excess pressure may damage fuel pressure regulator. Wait for fuel pressure to build. Slowly close valve on return pipe shutoff adapter. Using scan tool, command fuel pump on. If fuel pressure increases to greater than specification, go to step 21 . See «FUEL PRESSURE SPECIFICATIONS (EXCEPT SATURN)»(ref-129078-S11667363572001111200000) table. If fuel pressure does not increase to greater than specification, go to step 7 .
17. Check fuel pump electrical circuit. See appropriate diagnostic procedure under «NO-START DIAGNOSIS»(ref-129078-S21909973872001111200000) . Repair as necessary. After repairs, go to step 24 . If no problem is found, go to next step.
18. Remove fuel sending unit assembly. Inspect in-line fuel filter, fuel feed pipe and fuel pump strainer for restrictions. Check fuel pump flex pipe for leaks. Repair as necessary. After repairs, go to step 24 . If no problem is found, go to next step.
19. Replace fuel sending unit assembly. After repairs, go to step 24 .
20. Locate and repair loss of vacuum to fuel pressure regulator. After repairs, go to step 24 .
21. Replace fuel pressure regulator. After repairs, go to step 24 .
22. Locate and replace leaking fuel injector(s). After repairs, go to step 24 .
23. Locate and repair restriction in fuel return pipe. After repairs, go to step 24 .
24. Turn ignition off. Turn A/C system off. On all models except 2.2L and 2.4L, connect Fuel Pressure Gauge (J-34730-1A) to fuel pressure fitting on fuel rail. On 2.2L and 2.4L, install Fuel Pressure Gauge (J-29658-D). This kit modifies fuel pressure gauge so it may be installed in fuel delivery line with quick-connect fittings. On all models, place fuel pressure gauge bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition to obtain highest fuel pressure possible. Observe fuel pressure with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE SPECIFICATIONS (EXCEPT SATURN)»(ref-129078-S11667363572001111200000) table. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to step 11 .
25. Fuel pressure may vary slightly when fuel pump stops. After fuel pump stops, fuel pressure should stabilize and remain constant. Note fuel pressure when fuel pump stops running. If fuel pressure decreases more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, go to step 10 . If fuel pressure does not decrease more than 5 psi (0.3 kg/cm 2 ) in 10 minutes, system is okay.

FUEL PRESSURE SPECIFICATIONS (EXCEPT AURORA & SATURN)

FUEL SYSTEM PRESSURE TEST (AURORA)

1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK under DIAGNOSTIC SYSTEM CHECKS in appropriate SELF-DIAGNOSTICS article.
2. Ensure ignition is on. Using scan tool, command fuel pump on. If fuel pump operates, go to next step. If fuel pump does not operate, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(ref-129078-S09491341452001111300000) under NO-START - ENGINE CRANKS OKAY (3.5L & 4.0L AURORA)
3. Turn ignition off. Ensure fuel tank has adequate fuel. Turn A/C system off. Connect Fuel Pressure Gauge (J-34730-1A) to fuel pressure fitting on fuel rail. Pace fuel pressure gauge bleed hose into container. Turn ignition on. Bleed air out of fuel pressure gauge. Turn ignition off for 10 seconds. Turn ignition on. Fuel pump should run for about 2 seconds. Cycle ignition several times to obtain highest fuel pressure possible. Observe fuel pressure with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE SPECIFICATIONS (AURORA)»(ref-129078-S24482954442001111300000) table. If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to step 12 . FUEL PRESSURE SPECIFICATIONS (AURORA) Application (1) psi (kg/cm 2 ) 3.5L & 4.0L 41-47 (2.9-3.3) (1) Specification listed is with ignition on and engine off.
4. Fuel pressure may vary slightly when fuel pump stops. After fuel pump stops, fuel pressure should stabilize and remain constant. Note fuel pressure when fuel pump stops running. If fuel pressure decreases more than 5 psi in one minute, go to step 9 . If fuel pressure does not decrease more than 5 psi in one minute, go to next step.
5. Relieve fuel pressure until pressure is 10 psi. Monitor fuel pressure gauge for 5 minutes. If fuel pressure decreases more than 2 psi in 5 minutes, go to step 24 . If fuel pressure does not decrease more than 2 psi in 5 minutes, go to next step.
6. Turn ignition off for 15 seconds. Turn ignition on. Observe fuel pressure gauge. Start engine. If fuel pressure decreases 3-10 psi, go to next step. If fuel pressure does not decrease 3-10 psi, go to step 8 .
7. Operate vehicle within conditions of customers concern. If any scan tool parameters indicate a lean condition, go to step 17 . If no scan tool parameters indicate a lean condition, diagnose by symptom. See appropriate TROUBLE SHOOTING - NO CODES article.
8. Disconnect vacuum hose from fuel pressure regulator. With engine idling, apply 12-14 in. Hg of vacuum to fuel pressure regulator. If fuel pressure decreases by 3-10 psi, go to step 21 . If fuel pressure does not decrease 3-10 psi, go to step 23 .
9. Turn ignition off. Disconnect vacuum hose from fuel pressure regulator. Turn ignition on. Using scan tool, command fuel pump on. Check for fuel leak at pressure regulator vacuum port. If pressure regulator is leaking fuel, go to step 23 . If pressure regulator is not leaking fuel, go to next step.
10. Turn ignition off. Relieve fuel pressure. See «FUEL PRESSURE SPECIFICATIONS (AURORA)»(ref-129078-S24482954442001111300000) . Disconnect fuel supply and return hoses at fuel rail. Install Fuel Pipe Shutoff Adapters (J 37287) between fuel hoses and fuel rail pipes. Open valve on fuel pipe shutoff adapters. Place bleed hose into container. Turn ignition on. Using scan tool, command fuel pump on. Bleed air out of fuel pressure gauge. Using scan tool, command fuel pump on and off. Close valve on fuel supply pipe shutoff adapter. Monitor fuel pressure for one minute. If fuel pressure remains constant, go to step 19 . If fuel pressure does not remain constant, go to next step.
11. Turn ignition off. Open valve on fuel supply pipe shutoff adapter. Turn ignition on. Using scan tool, command fuel pump on and off. Close valve on return pipe shutoff adapter. Monitor fuel pressure for one minute. If fuel pressure remains constant, go to step 23 . If fuel pressure does not remain constant, go to step 20 .
12. If fuel pressure is more than 62 psi, go to step 14 . If fuel pressure is not more than 62 psi, go to next step.
13. If fuel pressure is more than zero psi, go to step 16 . If fuel pressure is zero psi, go to step 17 .
14. Turn ignition off. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (EXCEPT SATURN)»(ref-129078-S02634835662001111200000) . Disconnect fuel return pipe from fuel rail. Attach a flexible fuel hose to fuel rail return outlet passage. Place other end of flexible hose into container. Turn ignition on. Observe fuel pressure gauge with fuel pump running. Fuel pressure should be within specification. See «FUEL PRESSURE SPECIFICATIONS (AURORA)»(ref-129078-S11667363572001111200000) table. If fuel pressure is as specified, go to step 22 . If fuel pressure is not as specified, go to next step.
15. Inspect fuel rail outlet passage for restriction. Repair as necessary. After repairs, go to step 25 . If no restriction is found, go to step 23 .
16. Turn ignition off. Relieve fuel pressure. See «FUEL PRESSURE SPECIFICATIONS (AURORA)»(ref-129078-S24482954442001111300000) . Disconnect fuel supply and return hoses at fuel rail. Install Fuel Pipe Shutoff Adapters (J 37287) between fuel hoses and fuel rail pipes. Open valve on fuel pipe shutoff adapters. Place bleed hose into container. Turn ignition on. Using scan tool, command fuel pump on. Bleed air out of fuel pressure gauge. DO NOT allow fuel pressure to exceed 75 psi. Excess pressure may damage fuel pressure regulator. Wait for fuel pressure to build. Slowly close valve on return pipe shutoff adapter. Using scan tool, command fuel pump on. If fuel pressure increases to more than 47 psi, go to step 23 . If fuel pressure does not increase to more than 47 psi, go to next step.
17. Inspect fuel filter and fuel supply pipe for restrictions. Repair as necessary. After repairs, go to step 25 . If no problems are found, go to next step.
18. Inspect fuel pump connectors and ground circuit for poor connections. Repair as necessary. After repairs, go to step 25 . If no problems are found, go to next step
19. Remove fuel pump assembly. Fuel pump can be accessed through an inspection panel in trunk. Inspect fuel pump strainer for restrictions. Check fuel pump flex pipe for leaks. Check for contaminates in fuel tank. Repair as necessary. After repairs, go to step 25 . If no problems are found, go to step 24 .
20. Locate and replace leaking fuel injector(s). After repairs, go to step 25 .
21. Locate and repair loss of vacuum to fuel pressure regulator. After repairs, go to step 25 .
22. Locate and repair restriction in fuel return pipe. After repairs, go to step 25 .
23. Replace fuel pressure regulator. After repairs, go to step 25 .
24. Replace fuel pump. After repairs, go to next step.
25. Turn ignition off. Reconnect all disconnected connectors. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. If engine starts and continues to idle, system is okay. If engine does not start or continue to idle, go to step 3 .

FUEL SYSTEM PRESSURE TEST (SATURN)

Note. Ensure battery is fully charged when performing test.

1. Remove air induction tube. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELIEF (SATURN)»(ref-129078-S36295764382001111200000) . Install fuel pressure gauge and bleed off any fuel in system into container. Close fuel pressure gauge shutoff valve.
2. Turn ignition on. Using scan tool, command fuel pump on for at least 10 seconds. Allow pressure to stabilize. Record maximum fuel pressure. Ensure fuel pressure is as specified. See «FUEL PRESSURE SPECIFICATIONS (SATURN)»(ref-129078-S29341540272001111200000) table.
3. Bleed fuel pressure and repeat test at least 2 more times. If during test, fuel pressure drops more than 8 psi (.56 kg/cm 2 ) during a 5 minute period, isolate fuel supply side of fuel system by closing off return side with fuel pressure gauge shutoff valve.
4. Using scan tool, command fuel pump on. Allow fuel pressure to stabilize. Record maximum fuel pressure. If fuel pressure remains stable, replace fuel pressure regulator. If fuel pressure bleeds off more than 8 psi (.56 kg/cm 2 ), check fuel inlet line and injectors for leaks, and check for faulty fuel pump. Repair as necessary.

FUEL PRESSURE SPECIFICATIONS (SATURN)