GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2004 🢒 CTS 🢒 Preface 🢒 Cautions and Notices 🢒 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) leak diagnostic completes one test cycle. The malfunction indicator lamp (MIL) will illuminate after the EVAP leak diagnostic completes 2 test cycles for a large leak or up to 8 test cycles for a small leak, only when a condition is detected.

Diagnostic Aids
    • Operate the vehicle under the condition of the customers 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.
    • Movement of the EVAP pipes or fuel pipes may help find an intermittent condition.

Test Description

  1. This step tests for location of fuel leakage in the fuel lines.

    2.

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

    3.

  3. This step tests for a location of 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 tanks and the fuel pipes for damage or external leaks.

Did you find fuel leaking from the fuel tank?

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 you locate a fuel leak from the fuel pipes?

Go to Step 8

Go to Step 4

4

  1. Install the J 41415-40 Fuel Tank Cap Adapter.
  2. Connect the J 41413-200 Evaporative Emissions System Tester to the J 41415-40 .
  3. Command the EVAP vent valve ON with a scan tool.
  4. Pressurize the fuel tank with the J 41413-200 .
  5. Inspect for a fuel leak from the fuel tank.

Did you locate a fuel leak from the fuel tank?

Go to Step 7

Go to Step 5

5

  1. Turn the Nitrogen/Smoke valve on the J 41413-200 control panel to SMOKE.
  2. Use the remote switch to introduce smoke into the sealed system.
  3. Inspect the entire system with the with the J 41413-SPT High Intensity White Light for exiting smoke.

Did you locate a leak source?

Go to Step 6

Go to Diagnostic Aids

6

Repair the system as necessary.

Did you complete the repair?

System OK

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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 Hoses/Pipes Replacement - Filter to Tank and Fuel Hose/Pipes Replacement - Chassis .

Did you complete the replacement?

System OK

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