Diagnostic Procedure

WARNING: Gasoline or gasoline vapors are highly flammable. A fire could occur if an ignition source is present. Never drain or store gasoline or diesel fuel in an open container, due to the possibility of fire or explosion. Have a dry chemical (Class B) fire extinguisher nearby.

Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.2L CTS article.
Raise the vehicle. Inspect 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 ON, with engine OFF. With a scan tool, command the fuel pump ON. Inspect 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. Connect the Evaporative Emissions System Tester (EEST) to the fuel tank cap adapter. Using a scan tool, seal the EVAP system. DO NOT exceed 15 in. water. Using the EEST, pressurize the fuel tank. Did fuel leak from the fuel tank? If yes, go to step 7 . If no, go to next step.

NOTE: The fuel tank may need to be partially lowered.

Maintain pressure in the fuel tank using the EEST. Using the Ultrasonic Leak Detector, 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. After repair is completed, system is okay.
Replace fuel tank. See FUEL TANK under FUEL SYSTEMS in REMOVAL & INSTALLATION - CTS article. After repair is completed, system is okay.
Replace leaking fuel pipe. After repairs are complete, system is okay.