FUEL TANK CLUNK NOISE (DIAGNOSIS/INFORMATION)

SUBJECT: FUEL TANK CLUNK NOISE INFORMATION

VEHICLES AFFECTED: 1990-91 U VAN

This bulletin provides INFORMATION ONLY regarding a customer concern of an audible clunk noise experienced at vehicle acceleration and/or deceleration.

Condition:

----------- An audible physical clunk experienced at vehicle acceleration and/or deceleration. Also sometimes described and/or misdiagnosed as coilspring clunk,suspension clunk, fuel tank shift or engine cradle clunk.

Cause:

------ Fuel mass, as it shifts within the fuel tank, is colliding with the large radii at the ends of the fuel tank.

Note: Levels of fuel less than 3/4 full do not appear to create any clunking or vibration.

Do not attempt repairs to the suspension, fuel tank or try to add fuel tank strap insulation or fuel tank padding, none of these modifications have proven to work.

This information is being conveyed to keep our dealers and customers informed and to alleviate any unnecessary repairs.

When repair information becomes available, this bulletin will be updated.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.