GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 TrailBlazer - 2WD 🢒 Engine 🢒 Engine Controls - 4.2L 🢒 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, 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.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests for fuel leaks below the fuel tank fuel level.

    2.

  2. 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

Go to Diagnostic System Check - Vehicle

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.

  1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle .
  2. Inspect the fuel tank and the fuel pipes for damage or external leaks.

Did you find fuel leaking from the fuel tank?

Go to Step 6

Go to Step 3

3

  1. Turn ON the ignition, with the engine OFF.
  2. Command the fuel pump relay ON with a scan tool.
  3. Inspect for fuel leaking from the fuel pipes.

Did fuel leak from the fuel pipes?

Go to Step 7

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Install J 41413-200 Evaporative Emissions System Tester (EEST) and J 41415-40 Fuel Tank Cap Adapter or GE-41415-50 Interrupted Thread Cap Adapter.
  3. Test for a fuel tank leak referring to the J 41413-210 Operation Manual.

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

  4. Raise the vehicle. Refer to Lifting and Jacking the Vehicle .
  5. Inspect for a fuel leak while the system is under pressure.

Did fuel leak from the fuel tank?

Go to Step 6

Go to Step 5

5

  1. Using the J 41413-200 and the J 41413-210, introduce smoke into the evaporative emission (EVAP) system.

    2. Important: It may be necessary to partially lower the fuel tank. Refer to Fuel Tank Replacement .

  2. Inspect for leaks in any of the following locations:
    3. • The fuel tank, the fill limiter vent valve, the pressure relief valve, and the grade vent valves--Refer to Fuel Tank Replacement .
    • The fuel sender housing and fuel sender seal--Refer to Fuel Sender Assembly Replacement .
    • The fuel tank pressure (FTP) sensor seal--Refer to Fuel Tank Pressure Sensor Replacement .
    • The fuel fill pipe and hose

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.

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