Fuel Tank: Testing and Inspection

Fuel Tank Leak 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 when the evaporative emission (EVAP) leak diagnostic completes one test cycle. The malfunction indicator lamp (MIL) will illuminate after the EVAP leak diagnostic completes two test cycles for a large leak or up to eight test cycles for a small leak, only when a condition is detected.

Diagnostic Aids

* 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.
* Movement of the EVAP pipes or fuel pipes may help find an intermittent condition.

Test Description

Step 1 - Step 8:

3. This step tests for location of fuel leakage in the fuel lines.
4. This step tests for fuel leaks below the fuel level in the fuel tank.
5. This step tests for a location of fuel vapors escaping above the fuel level in the fuel tank.