Fuel System Diagnosis

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 6275341 Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions Circuit/System Description For an overview of the component/system, refer to: Fuel System Description Reference Information Schematic Reference Engine Controls Schematics Connector End View Reference Master Electrical Component List Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References Circuit/System Verification

Note

Verify the fuel tank is not empty before proceeding. Inspect the fuel system for damage or external leaks before proceeding.

1. Verify DTC P018B, P018C, P018D, P0191, P0192, P0193, P127C, P127D is not set. ⇒ If DTC P018B, P018C, P018D, P0191, P0192, P0193, P127C, P127D is set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If DTC P018B, P018C, P018D, P0191, P0192, P0193, P127c, P127D is not set
2. Ignition » On / Vehicle » In Service Mode
3. Perform the scan tool control function: Fuel Pump — Command the function On several times. Verify the scan tool parameter: Fuel Pressure Sensor = 370 to 450 kPa (54 to 65 PSI) ⇒ If less than 370 kPa (54 PSI) Refer to: Circuit/System Testing ⇒ If greater than 450 kPa (65 PSI) Refer to: Fuel Return System Diagnosis ⇓ If between 370 and 450 kPa (54 and 65 PSI)
4. Engine » Cranking / Running — For 10 s Verify the scan tool parameter: Fuel Rail Pressure Sensor = Greater than 13 MPa (1,885 PSI) ⇒ If 13 MPa (1,885 PSI) or less Refer to: Fuel System Diagnosis - High Pressure Side ⇓ If greater than 13 MPa (1,885 PSI)
5. Engine » Cranking Verify the function: Engine = Running ⇒ If the function does not work Refer to: Fuel System Diagnosis - High Pressure Side ⇓ If the function works
6. Engine » Running Verify the following conditions do not exist: Engine Stalled Engine Idle Speed Not Stable Engine Misfire Exhaust » Smoke ⇒ If a condition exists Refer to: Fuel System Diagnosis - High Pressure Side ⇓ If no condition exists
7. Refer to: Symptoms - Engine Controls Circuit/System Testing
8. Verify the following conditions do not exist: Poor component electrical connections: Fuel Pump — Electrical Connector Fuel Feed Pipe — Leaking / Restricted » Refer to: Fuel Leak Diagnosis Fuel Return Pipe — Leaking / Restricted » Refer to: Fuel Leak Diagnosis ⇒ If a condition exists Repair or replace as necessary ⇓ If no condition exists
9. Verify the condition does not exist: Fuel Filter » Restricted ⇒ If the condition exists Replace the component: Fuel Filter ⇓ If no condition exists
10. Test or replace the component: A7 Fuel Tank Fuel Pump Module Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Fuel Filter Replacement Fuel Tank Fuel Pump Module Replacement — A7 Fuel Tank Fuel Pump Module