GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 XLR 🢒 Engine 🢒 Engine Controls - 4.6L (LH2) 🢒 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) 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 tanks
       - The fuel feed pipe
    • Test for fuel vapor leaks in the following locations:
       - The fuel tanks, fill limiter vent valve, and rollover valves
       - The fuel fill pipe, hose and fuel fill cap
       - Both fuel tank modules and seals
       - The fuel tank pressure (FTP) sensor seal
       - The EVAP vapor pipe
       - The fuel tank crossover tube/hose
    • 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 step tests for fuel leaks below the fuel tank fuel level.

    2.

  2. This step locates fuel vapors escaping above the fuel level in the fuel tanks.

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 tanks and 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 ON with a scan tool.
  3. Inspect for fuel leaking from the fuel pipes.

Did you find fuel leaking from the fuel pipes?

Go to Step 7

Go to Step 4

4

  1. Install the J 41415-40 Fuel Tank Cap Adaptor.
  2. Connect the J 41413-200 Evaporative Emissions System Tester (EEST) to the fuel tank cap adaptor.
  3. Command the EVAP vent solenoid ON with a scan tool.

    4. Important : Do not exceed 15 in H2O.

  4. Pressurize the fuel tanks with the J 41413-200 .

Did you find fuel leaking from the fuel tanks?

Go to Step 6

Go to Step 5

5

  1. Maintain pressure in the fuel tanks with the J 41413-200 .

    2. Important: It may be necessary to partially lower the fuel tanks. Refer to Fuel Tank Replacement - Left Side or Fuel Tank Replacement - Right Side .

  2. With the J 41416 Ultrasonic Leak Detector, test for leaks above the fuel level in the following locations:
    3. • The fuel tanks, fill limiter vent valve, pressure relief valve and rollover valves--Refer to Fuel Tank Replacement - Left Side or Fuel Tank Replacement - Right Side .
    • The fuel tank pressure (FTP) sensor seal--Refer to Fuel Tank Pressure Sensor Replacement .
    • The fuel fill pipe and hose--Refer to Filler Tube Replacement or Fuel Tank Filler Hose 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 - Left Side or Fuel Tank Replacement - Right Side .

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 in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2