GM Service Manual Online
For 1990-2009 cars only

The diagnosis of fuel odor may be a condition of a leaking fuel tank, filler neck, or filler cap. A defective filler cap, or a plugged or pinched vent pipe can cause a collapsed fuel tank. Loose mounting straps or foreign material in the tank may be the cause of a rattle at the fuel tank.

Warning: Place a dry chemical (Class B) fire extinguisher near the area before performing a Fuel Tank Leak Check. Before removing the fuel tank for a suspected leak, make sure that the fuel pipes or the tubes are not leaking onto the tank. Once removed, make sure that the fuel is not leaking around the fuel sender O-ring. Failure to follow these precautions may result in personal injury.

  1. This test requires the fuel sender and O-ring to be installed.
  2. Warning: Refer to Battery Disconnect Warning in the Preface section.

  3. Disconnect the battery cables.
  4. Drain the fuel tank. Refer to Fuel Tank Draining.
  5. Remove the fuel tank. Refer to Fuel Tank Replacement.
  6. Cap the fuel feed tube and the fuel return tube on the fuel sender.
  7. Connect a piece of hose to the filler tube nipple and plug the opposite end.
  8. Apply a soap solution to the outside of the fuel tank.
  9. Apply 3.5 kPa (0.5 psi) air pressure to the vent hose of the fuel tank. A leak will show up as bubbles.