FUEL LINE KNOCK/RATTLE NOISE NEW FUEL PRESSURE REGULATOR

SUBJECT: FUEL LINE KNOCK/RATTLE (NEW FUEL PRESSURE REGULATOR)

VEHICLES AFFECTED: 1989-90 'A' AND 'N' MODELS WITH 3300 ENGINE (VIN N)

Some 1989-90 A and N vehicles equipped with the 3300 engine (VIN N) may exhibit a light knock/rattle type noise, audible after a cold start at ambient temperatures below 4 C (40 F) .

The noise may be audible either in or outside of the vehicle from start-up until the engine is up to normal operating temperatures.

This condition is caused by fuel system pulsations generated by fuel injector operation causing a hydraulic hammering in the chassis fuel pipes.

Vehicles exhibiting this condition may be repaired by installing a new design fuel pressure regulator, Part Number 17112611. The new Fuel Pressure Regulator has a reduced seat orifice and the orifice chamfer has been removed.

IMPORTANT: THE NEW FUEL PRESSURE REGULATOR, PART NUMBER 17112611 WILL ALSO BE THE NEW SERVICE REPLACEMENT REGULATOR FOR THE 1989-90 3300 ENGINE (VIN N), REPLACING PART NUMBER 17112117.

WARRANTY INFORMATION:

Use applicable "J" operation for replacement of Fuel Pressure Regulator.

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.