GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Uplander Ext. 🢒 Engine 🢒 Engine Controls - 3.5L (LX9) 🢒 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 emissions (EVAP) diagnostics complete one test cycle. The malfunction indicator lamp (MIL) will illuminate after the EVAP diagnostics complete 2 test cycles.

Diagnostic Aids
    • Operate the vehicle under the condition of the customer's 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 fuel feed pipe
    • Test for fuel vapor leaks in the following locations:
       - The fuel tank, fill limiter vent valve and rollover valves
       - The fuel fill pipe, hose and fuel fill cap
       - The fuel sender housing and seal
       - 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.

Test Description

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

  1. This test is to locate fuel leakage in the fuel lines.

    2.

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

    3.

  3. This test is to locate fuel vapors escaping above the fuel level in the fuel tank .

Fuel Tank Leak Test

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Important: Before performing this procedure, place a dry chemical (class B) fire extinguisher near the work area.

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

Did you find fuel leaking from the fuel tank or fuel pipes?

Go to Step 7

Go to Step 3

3

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

Did fuel leak from the fuel pipe?

Go to Step 8

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Install the GE-41415-50 Interrupted Thread Fuel Tank Cap Adapter.
  3. Connect the J 41413-200 Evaporative Emissions System Tester (EEST) to the GE-41415-50 .
  4. Turn ON the ignition, with the engine OFF.
  5. Seal the evaporative emission (EVAP) system with a scan tool.
  6. Connect the nitrogen/smoke hose to the 0.5 mm (0.20 in) test orifice on the bottom-front of the J 41413-200 .
  7. Turn ON the ignition, with the engine OFF.
  8. Seal the EVAP system with a scan tool. Refer to Scan Tool Output Controls .
  9. Activate the J 41413-200 with the remote switch and pressurize the fuel tank with nitrogen.

Did fuel leak from the fuel tank?

Go to Step 7

Go to Step 5

5

  1. Connect the J 41413-200 power supply clips to a known good 12-volt source.
  2. Turn ON the ignition, with the engine OFF.
  3. Command the EVAP canister vent solenoid valve closed with a scan tool.
  4. Turn the nitrogen/smoke valve on the J 41413-200 control panel to SMOKE.
  5. Introduce smoke into the EVAP system with the remote switch.
  6. Continue to introduce smoke into the fuel tank assembly for an additional 60 seconds.
  7. Inspect the entire fuel tank assembly for exiting smoke with the J 41413-SPT High Intensity White Light.
  8. Continue to introduce smoke at 15-second intervals while observing the fuel tank assembly for leaks in any of the following locations:
    9. • The fuel tank, fill limiter vent valve, pressure relief valve and rollover 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 EVAP vapor lines and hoses
    • The fuel fill pipe and hose

Did you locate a fuel tank assembly leak?

Go to Step 6

Go to Diagnostic Aids

6

Repair the system, as necessary.

Did you complete the repair?

System OK

--

7

Replace the fuel tank. Refer to Fuel Tank Replacement .

Did you complete the repair?

System OK

--

8

Replace the leaking fuel pipe. Refer to Fuel Hose/Pipes Replacement - Chassis .

Did you complete the replacement?

System OK

--