Diagnostic Aids
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Operate the vehicle under the condition of the customers concern. Under high temperature conditions fuel vapors may increase to the point of EVAP canister vapor saturation. Fuel vapors would then be released into the atmosphere. Once the engine is running and EVAP purge is enabled, all fuel vapor release would be eliminated.
- Test for fuel leaking in the following locations:
- The fuel tank
- The rear tank, if applicable
- The fuel feed and return pipes
- Test for fuel vapor leaks in the following locations:
- The fuel tank, fill limiter vent valve and rollover valves
- The rear fuel tank and rollover valves, if applicable
- The fuel fill pipe, hose and fuel fill cap
- The rear fuel fill pipe, hose and fuel fill cap, if applicable
- The fuel sender housing and seal.
- The rear fuel sender housing and seal, if applicable
- The fuel tank pressure (FTP) sensor seal
- The EVAP vapor pipe
- Movement of the EVAP pipes or fuel pipes may help find an intermittent condition.