Diagnostic Procedure

Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.1L CENTURY, GRAND PRIX & MALIBU article.

NOTE: Before performing this procedure, place a dry chemical (class B) fire extinguisher near the work area.

Raise and support the vehicle. Check the fuel tank and fuel pipes for damage or external leaks. Did you find fuel leaking from the fuel tank? If yes, go to step 7. If no, go to next step.
Turn ignition switch to RUN position, engine OFF. Using a scan tool, command the fuel pump ON. Check for fuel leaking from the fuel pipes. Did fuel leak from the fuel pipes? If yes, go to step 8. If no, go to next step.
Install the Fuel Tank Cap Adapter (J 41415-40). Connect the EVAP Pressure/Purge Diagnostic Station (J 41413) to the fuel tank cap adapter. Using a scan tool, seal the EVAP system. DO NOT exceed 15 in. H2O. Using the EVAP pressure/purge diagnostic station, pressurize the fuel tank. Did fuel leak from the fuel tank? If yes, go to step 7. If no, go to next step.
Using the EVAP pressure/purge diagnostic station, maintain pressure in the fuel tank. The fuel tank may need to be partially lowered. Using the Ultrasonic Leak Detector (J 41416), test for leaks above the fuel level in the following locations.
- The fuel tank, fill limiter vent valve, pressure relief valve and rollover valves.
- The fuel sender housing and fuel sender seal.
- The Fuel Tank Pressure (FTP) sensor seal.
- The EVAP vapor pipes.
- The fuel fill pipe and hose.
Did you locate a fuel leak? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
Repair the system as necessary.
Replace the fuel tank.
Replace the leaking fuel pipe.