ELECTRIC FUEL PUMP NOISE DIAGNOSIS AND NEW PARTS

ELECTRIC FUEL PUMP NOISE AUDIBLE IN THE PASSENGER COMPARTMENT

MODELS AFFECTED: SOME 1984 THROUGH 1988 CENTURYS; 1985 ---------------- THROUGH 1988 ELECTRAS; 1986 THROUGH 1988 LESABRES, AND 1988 REGALS EQUIPPED WITH PORT FUEL INJECTED ENGINES (VIN CODES 3, B, C, L, AND W)

NOTICE: This bulletin supersedes several previous fuel pump noise communications including bulletins: 85-6C-2, 85-6C-18, 86-6E-13, 87-6C-6 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:

CENTURYS (Coupe, Sedan, and Wagon)

1984 through 1988 Centurys which have fuel pump noise and could not be corrected by proper fuel tank isolation (bulletin 87-6C-3) and/or a new double convexed metal cover pulsator, Part Number 25094266 (See Figure 1), may require a turbine style fuel pump as listed on the next page:

1984 and 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 a 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) 25004740

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 from GMSPO.

NOTE: Turbine fuel pumps do not mount to roller vane (non-turbine) pump senders due to their larger size (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 1984 or 1985 Century, the identification label would be either an APA or APB.

WARRANTY INFORMATION

Use applicable labor operation number and labor time.

ELECTRAS/PARK AVENUES AND LESABRES (Coupe and Sedan) ---------------------------------- 1988 Buick Electras and Park Avenues manufactured after VIN J1637630 and LeSabres built after VIN JH468816, were assembled with turbine design fuel pumps which greatly reduce or eliminate fuel pump noise. Although the Electra turbine pump is a different style than the LeSabre currently uses, they both have the same quiet quality.

1985 through 1988 Electras built prior to VIN J1637630, and 1986 through 1988 LeSabres built prior to JH468816 which have fuel pump noise and could not be corrected by proper fuel tank isolation (Bulletin 86-6C-2) 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:

1985 Electra/Park Avenue Part Numbers ------------------------ ------------ Complete Fuel Pump/Sender Assembly 25091007

Replacement Components

Fuel Sending Unit Kit 25094867 Fuel Pump Kit 25116144 Pump to Sender Retaining Clamp 25527699 Identification Label Codes if a Turbine Pump has been installed (See Figure 2) CET

1986 Through 1988 Electras/Park Avenues and, 1986 Through 1988 LeSabres Built Prior to VIN JH468816 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 LeSabres Built After JH468815

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 the above part numbers are currently available 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.

NOTE: 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 Electra/Park Avenue, the identification label would be CET.

When installing a turbine pump in 1985 through 1988 Electras and LeSabres, make certain the fuel pickup 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 LeSabres built after VIN JH468815, place the fuel pickup 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 pickup 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 pickup screen upward while rotating and maneuvering the pump/sender assembly into the tank (See Figure 6).

1988 Regals

Some 1988 Regals assembled prior to VIN J1421781 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 feature (CCV) 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 sender 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 Number: 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.