NEW DESIGN FUEL SYSTEM TO REDUCE FUEL PUMP NOISE

MODELS AFFECTED: 1985-87 CENTURY COUPES AND SEDANS WITH (LB6, VIN W), (LN3, VIN 3), (LG2, VIN B), (LG3, VIN 3)

Some 1985-87 Century sedans and coupes with V-6 engines (RPO LB6, LG3, or LN3), may exhibit what is considered to be an objectionable level of fuel pump noise audible in the vehicle passenger compartment.

This objectionable level of noise may be attributed to any of the components or conditions noted below: 1. Fuel Pump 2. Pulsator 3. Inadequate pump discharge port to sender feed pipe clearance. 4. Improper tank to underbody position/ isolation resulting in ground out.

Vehicles exhibiting this condition may be repaired by following the procedure below:

1. Drain and lower fuel tank following applicable Buick Chassis Service Manual procedures.

2. Remove existing anti-squeak material from tank and discard.

3. Clean top of fuel tank and remove fuel sender/pump assembly.

4. Remove and discard pulsator. Inspect to ensure a minimum distance of 1/4" exists between pump discharge port and sender feed pipe, (See Figure 1). Replace sender as required (see GMSPO parts catalog for correct application).

5. Inspect pump under foam isolation sleeve for part number. If part number is either 6442409 or 6442439, replace pump (see GMSPO part catalog for correct application).

6. Reassemble sender/pump assembly utilizing new pulsator, Part Number 25093965, ensuring pump and pulsator are positioned properly (Figure 1).

7. Install sender/pump assembly into fuel tank utilizing new fuel sender O-ring, Part Number 22515965.

8. Cut each of the long isolation strips contained in Sound Isolation Kit, Part Number 22530899, to lengths noted below:

2 pcs. - 3-1/2" 2 pcs. - 4-1/2" 1 pc. - 8"

9. Position isolation material to top of fuel tank, (Figure 2).

10. Position and secure fuel line separator contained in isolation kit as shown by applicable model year (Figure 3).

11. Raise and position fuel tank to vehicle underbody. Loosely attach straps to underbody, placing two 7/16" flat washers, Part Number 3899696, or equivalent, on each of the strap bolts between strap and underbody attaching point (Figure 4).

12. Ensure fuel tank strap spacer located on L.H. strap is properly positioned under forward flange of tank (Figure 5). Torque L.H. strap bolt and then R.H. bolt to 25 ft. lbs. (34 N.m)

13. Inspect to ensure forward tank flange is not contacting strap body bracket, and that sender pipes are not in contact with either tank or underbody. Correct as required.

14. Reconnect fuel hoses and electrical connector following Buick Chassis Service Manual procedure.

15. Start vehicle, inspect for any fuel leakage and repair as necessary.

Parts that are required for this procedure are available from GMSPO and are noted below, excluding applicable pump and sender part numbers which can be procured from GMSPO Parts Catalog.

Part Number Description Quantity Required ----------- ----------- ------------------ 22530899 Sound Isolation Kit 1 25093965 Pulsator 1 3899696 7/16" Flat Washer or Equivalent 4 *22515965 Fuel Sender O-ring 1

*O-ring is included with fuel sender or pump service kit and separate ordering is not required when either of these components are replaced.

WARRANTY INFORMATION

Labor Operation Number: T5122 Labor Time: 1.2 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.