ELECTRIC FUEL PUMP NOISE DIAGNOSIS AND NEW PARTS

Models 1984-88 6000, 1987-88 BONNEVILLE AND 1988 AFFECTED: GRAND PRIX EQUIPPED WITH PORT FUEL INJECTED ENGINES (VIN CODES 3,C AND W)

"This bulletin supersedes several previous fuel pump noise communications including bulletins: 85-6c-2, 85-6C-18, and 86-6 (Gasoline)-46 and all DCS messages due to the recent availability of turbine and contained check valve fuel pumps and a change in the service correction procedure. Please discard all previous communications listed above and replace them with this revision."

Some models equipped with port fuel injected engines may develop a fuel pump noise condition which some customers might consider to be at an objectionable level.

Although various components and/or ground out conditions can contribute to this noise level (i.e., pulsators, interference between the fuel lines, fuel tank, and underbody), the root cause of this condition is the fuel pump.

To repair this condition, use the service procedure listed below for the appropriate year and model application.

6000 (Coupe, Sedan, and Wagon)

The 1985-88 6000 models which have fuel pump noise and could not be corrected by proper fuel tank isolation (Bulletin 87-6(Gasoline)-41A) and/or a new double convexed metal cover pulsator, Part Number 25094266 (see Figure 1), may require a turbine style fuel pump as shown in the following list:

1985 Part Numbers ---- ------------- Complete Fuel Pump/Sender Assembly 25091847 Replacement Components: Fuel Sending Unit Kit N/A Fuel Pump Kit 25116144 Pump to Sender Retaining Clamp 25527699 Identification Label Codes if a Turbine Pump has been installed (See Figure 2) APA or APB

1986

Complete Fuel Pump/Sender Assembly 25092920 Replacement Components: Fuel Sending Unit Kit 25094739 Fuel Pump Kit 25116144 Pump to Sender Retaining Clamp 25527699 Identification Label Codes if Turbine Pump has been installed (See Figure 2) APL or APM

1987 and 1988

Complete Fuel Pump/Sender Assembly (Digital Dash) 25093077 Complete Fuel Pump/Sender Assembly (Non-Digital Dash) 25093079 Replacement Components: Fuel Sending Unit Kit (Replaces Digital and Non-Digital) 25094740 Fuel Pump Kit 25116144 Pump to Sender Retaining Clamp 25527699 Identification Label Codes if a Turbine Pump has been installed (See Figure 2) APN or APP

Parts are currently available at GMSPO.

NOTICE:Turbine fuel pumps do not mount to roller vane (non-turbine) pump senders (see Figure 3). When making repairs or ordering parts, it can be determined if a turbine design pump is in the vehicle prior to removing it from the fuel tank by inspection of the identification label. Compare the identification label codes listed in this bulletin with those on the sender harness of the vehicle. Any identification code other than those listed would indicate a roller vane design pump is in the vehicle.

Example: If a turbine design fuel pump assembly is in a 1985 6000, the identification label would be either an APA or APB.

WARRANTY INFORMATION

Use applicable labor operation number and labor time.

BONNEVILLE (Sedan)

The 1988 Bonneville models built after VIN JW253387, were assembled with turbine design fuel pumps which greatly reduce or eliminate fuel pump noise.

Vehicles built prior to JW253387 which have fuel pump noise and could not be corrected by proper fuel tank isolation and/or a new double convexed metal cover pulsator, Part Number 25094266 (see Figure 1) , may also require a turbine style fuel pump. However, because of their larger diameter, they must either be installed as a complete assembly, or mounted to the appropriate fuel sender listed below:

1987-88 Bonnevilles Built Prior to VIN JW253387 Part Number ----------------------- ----------- Complete Fuel Pump/Sender Assembly (Digital Dash) 25092921 Complete Fuel Pump/Sender Assembly (Non-Digital Dash) 25092922 Replacement Components: Fuel Sending Unit Kit (Replaces Digital and Non-Digital) 25094732 Fuel Pump Kit 25116144 Pump To Sender Retaining Clamp 25527699 Identification Label Codes if a Turbine Pump has been installed (See Figure 2) CPB or CPC

1988 Bonneviles Built Built After VIN JW253387 ------------------------ Replacement Components: Fuel Sending Unit Kit 25093316 Fuel Pump Kit 25116296 Pulsator 25094266 Identification Label Codes if a Turbine Pump has been installed (See Figure 2) CPD, CPE or CPP

All of the above part numbers are currentlv at GMSPO, except 25116296 which is expected to be available on September 9, 1988. Until then normal part orders will not be accepted by GMSPO.

NOTICE: Turbine fuel pumps do not mount to roller vane (non-turbine) pump senders (see Figure 3) . When making repairs or ordering parts, it can be determined if a turbine design pump is in the vehicle prior to removing it from the fuel tank by inspection of the identification label. Compare the identification label codes listed in this bulletin with those on the sender harness of the vehicle. Any identification code other than those listed would indicate a roller vane design pump is in the vehicle.

When installing a turbine pump in 1987-88 Bonneville models, make certain the fuel pick-up screen is parallel with the edge of the float, and the pump to sender retaining clamp is positioned close to the float arm, yet not interfering with the float arm's movement (see Figure 4) .

When replacing fuel pump/sender assembly components on 1988 Bonneville models built after VIN JW235386, place the fuel pick-up screen at a one o'clock position when compared to the fuel level float, and position the pulsator so its metal cover faces directly opposite the pick-up screen (see Figure 5) .

WARRANTY INFORMATION

Use applicable labor operation number and labor time.

To install either design turbine pump assembly in the fuel tank, bend the fuel pick-up screen upward while rotating and maneuvering the pump/sender assembly into the tank.

1988 Grand Prix

Some 1988 Grand Prix models assembled prior to VIN JF202360 may exhibit an increased level of fuel pump noise audible in the vehicle passenger compartment.

This condition may be addressed by installing a new fuel pump with a contained check valve (CCV) feature and new tank to underbody insulator pads that have been released as an interim production change.

Service procedure and parts available from GMSPO are indicated below:

Service Procedure

1. Drain and lower fuel tank following applicable shop manual procedures.

2. Remove fuel tank sender and pump assembly.

3. Remove existing anti-squeak material from tank and discard. Clean top of tank.

4. Position and secure eight (8) insulator pads, Part Number 10114724, to the top of fuel tank as shown in Figure 7.

5. Remove fuel pump from sender assembly and discard.

6. Inspect pulsator to ensure it is of the latest design with double convexed metal cover (see Figure 1) . If not this style, discard and replace with Part Number 25094266, making sure to maintain a minimum 1/4" gap between pump discharge port and sender feed pipe (see Figure 8) .

7. Reassemble sender pump assembly utilizing new fuel pump contained in fuel pump kit, Part Number 25116156.

8. Install sender/pump assembly into fuel tank utilizing new fuel sender O-Ring contained in fuel pump kit.

9. Inspect tank assembly to ensure fuel and vapor pipes are properly positioned and retained in fuel line separators/spacers. When properly installed, separators/spacers should contact tank top while clearance is maintained between pipes and tank.

10. Raise and position fuel tank to vehicle underbody and secure in position, torquing strap bolts to 25 ft. lbs.

11. Inspect and correct any obvious tank or serider pipe(s) contact with vehicle underbody.

12. Reconnect fuel/vapor hoses and electrical connector.

13. Start vehicle, inspect for any fuel leakage and repair, as required.

Part Description Part Number ---------------- ----------- Fuel Pump Kit 25116156 Insulator Pad Unit (8 pcs/unit) 10114724 Pulsator *25094266

* Only required when existing pulsator is of old style (reference Step 6).

Parts are currently available from GMSPO.

WARRANTY INFORMATION

Labor Operation: T1324 Labor Time : 1.1 Hours Trouble Code : 92

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.