GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2003 🢒 LeSabre 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 Fuel Tank Leak Test

Circuit 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) diagnostics complete one test cycle. The malfunction indicator lamp (MIL) will illuminate after the EVAP diagnostics complete two test cycles.

Diagnostic Aids
    • Operate the vehicle under the condition of the customer's concern. Under high temperature conditions the 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.
    • Test for fuel leaking in the following locations:
       - The fuel tank
       - The fuel feed and return pipes
    • 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
    • Moving the EVAP pipes or the fuel pipes may help find an intermittent condition.

Test Description

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

  1. Perform this procedure in order to determine that no EVAP diagnostic DTC is present.

  2. This test locates fuel leakage in the fuel pipes.

    3.

  3. This tests for fuel leaks below the fuel tank fuel level.

    4.

  4. This test locates fuel vapors escaping above the fuel level in the fuel tank .

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

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 in General Information.
  2. Inspect the fuel tank and the fuel pipes for damage or for 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 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 the J 41413-200 Evaporative Emissions System Tester (EEST) and the J 41415-40 Fuel Tank Cap Adapter.
  3. Test for a leak referring to the J 41413-210 Operator 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 in General Information.
  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 theJ 41413-200 and the J 41413-210 Operation Manual, introduce smoke into the evaporative emission (EVAP) system.

    2. Important: The fuel tank may need to be partially lowered . 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 rollover valves
    • Refer to Fuel Tank Replacement .
    • The fuel sender housing and fuel sender seal
    • The fuel tank pressure (FTP) sensor seal
    • The EVAP vapor pipes
    • The fuel fill pipe and hose
    • Refer to Filler Tube 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?

System OK

--

7

Replace the leaking fuel pipe. Refer to Fuel Hoses/Pipes Replacement - Filter to Tank .

Did you complete the replacement?

System OK

--

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