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.
• | 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. |
The numbers below refer to the step numbers on the diagnostic table.
This step tests for fuel leaks below the fuel tank fuel level.
This step tests for fuel vapors escaping above the fuel level in the fuel tank.
Step | Action | Yes | No | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |||||||||
2 |
Caution: 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. Did you find fuel leaking from the fuel tank? | Go to Step 6 | Go to Step 3 | ||||||||
3 |
Did fuel leak from the fuel pipes? | Go to Step 7 | Go to Step 4 | ||||||||
Important: If the floating indicator registers any flow after stabilizing, a leak is evident. Did fuel leak from the fuel tank? | Go to Step 6 | Go to Step 5 | |||||||||
Important: It may be necessary to partially lower the fuel tank. Refer to Fuel Tank Replacement .
Did you find and correct the condition? | Go to Step 8 | Go to Diagnostic Aids | |||||||||
6 | Replace the fuel tank. Refer to Fuel Tank Replacement . Did you complete the replacement? | Go to Step 8 | -- | ||||||||
7 | Replace the leaking fuel pipe. Refer to Fuel Hose/Pipes Replacement - Chassis . Did you complete the replacement? | Go to Step 8 | -- | ||||||||
8 | Operate the system under the condition of the customer concern in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |