Fuel Tank: Testing and Inspection

Fuel Tank Leak Test

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provides an overview of each diagnostic category.

Test Description

The fuel tank leak test is used to locate any fuel or fuel vapor escaping the fuel tank area. Fuel vapors escaping above the fuel level will be detected, if more than the calibrated amount, when the evaporative emission (EVAP) diagnostics complete one test cycle. The malfunction indicator lamp (MIL) will illuminate after the EVAP diagnostics have failed 2 test cycles.

Diagnostic Aids

* Operate the vehicle under the condition of the customer 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 the EVAP purge is enabled, all fuel vapor release would be eliminated.
* Movement of the EVAP pipes or the fuel pipes may help find an intermittent condition.
* If the fuel level is low, a liquid fuel leak may not be evident.

Reference Information
Special Tools

* GE 41415-50 - Interrupted Thread Cap Adapter
* J 41413-200 - Evaporative Emissions System Tester (EEST)

System Verification

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.

* Inspect the fuel tank and the fuel pipes for damage or external leaks.
* Turn ON the ignition, with the engine OFF. Command the fuel pump relay ON with a scan tool. Inspect for fuel leaking from the fuel pipes.

System Testing

Note: If the floating indicator registers any flow after stabilizing, a leak is evident.

1. Turn OFF the ignition. Install the J 41413-200 - EEST and the GE 41415-50 - Cap Adapter. Test for a fuel leak while the system is under pressure referring to the J 41413-210 Operation Manual.

Note: It may be necessary to partially lower the fuel tank.

2. Using the J 41413-200 - EEST and the J 41413-210 Operation Manual, introduce smoke into the evaporative emission (EVAP) system. Inspect for leaks in any of the following locations:

* The fuel tank, the fill limiter vent valve, the pressure relief valve, and the grade vent valve
* The fuel sender, the fuel sender seal, the fuel pipe, and the EVAP pipes
* The fuel tank pressure (FTP) sensor seal
* The fuel fill pipe and hose

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Evaporative Emission Hoses/Pipes Replacement - Canister/Fuel Tank (Evaporative Emission Hoses/Pipes Replacement - Canister/Fuel Tank)
* Fuel Hose/Pipes Replacement - Chassis (Service and Repair)
* Fuel Sender Assembly Replacement (Service and Repair)
* Fuel Tank Replacement (Removal and Replacement)