For 1990-2009 cars

# FUEL PUMP NOISE AT LOW SPEEDS OR AT IDLE - CORRECTION

#### VEHICLES AFFECTED: 1984 - 1985 Buick and Oldsmobile 'A' and 'C' Models MPFI Equipped

#### CONDITION:

---------- Some 1984 and 1985 Buick and Oldsmobile 'A' and 'C' models may exhibit an abnormal noise condition during low speed and idle situations that originates at the fuel tank and is transmitted into the passenger compartment.

#### CAUSE & CORRECTION:

The noise may be caused by:

1. Fuel tank contacting the underside of the vehicle floor pan.

To Determine if the noise is due to the tank contacting the floor pan, it will be necessary to lower the fuel tank approximately 2 inches from the floor pan and re-evaluate the noise. If the noise diminishes, carefully inspect the top side of the fuel tank for contact locations and correct as necessary. When installing the fuel tank, it is imperative that the tank-to-body insulator (Figure 1) is properly installed and that the tank retaining strap bolts are not OVER tightened.

2. Fuel pump.

If the noise is originating from the fuel pump, a new design 'finger drive' pump, part number 25115429 is now available through GM Parts. This part does not include a fuel strainer, part number 25055176 that may be required for installation if the old one is damaged during removal. The 'finger drive' pump includes the improved retention posi-lock terminals, therefore, it may be necessary to change the wire terminals on the tank sender unit leads for correct installation. Use care when installing the pump to assure that the isolator (bottom of pump) and the pulsator (Figure 2) are properly positioned to prevent the pump from contacting the tank sender unit.

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.