HARD/NO START (REPLACE FUEL DAMPENER, STRAINER,FILTER)

SUBJECT: HARD START/NO START (REPLACE FUEL PULSE DAMPENER, FUEL PUMP STRAINER AND INLINE FUEL FILTER)

VEHICLES AFFECTED: 1991 "W" MODELS WITH 3.1L ENGINE (METHANOL/VARIABLE FUEL VEHICLE)

APPLICATION:

----------- 1991 Chevrolet Lumina - Variable Fuels (VFV) (Nl4 Option) Only, 3.1L Engine (VIN T - RPO LHO)

CONDITION:

--------- Some variable fuel vehicles may exhibit a hard start or no start condition.

CAUSE:

----- Flurosilicone fuel pump pulse dampener seals may degrade over time in methanol fuel blends and cause inadequate fuel flow to the engine under some conditions.

CORRECTION:

---------- Follow appropriate 1991-92 Chevrolet Lumina Service Manual Supplement (ST379-91/92M) procedures when diagnosing or correcting fuel related problems. When the above symptoms are present, verify the condition by checking the fuel system pressure for pressure loss after engine is shut off. If diagnosis indicates fuel pressure loss, a possible cause is degradation of the fuel pulse dampener. Vehicles may be repaired by installing a new variable fuel pulse dampener that is white in colour and contains black viton seals.

NOTICE:

When servicing any variable fuel sender or fuel pump, inspect the fuel pulse dampener seals, if orange (fluorosilicone) in colour, install a new variable fuel pulse dampener with black (viton) seals and white housing.

It is always necessary to replace the fuel pump strainer at the same time, when replacing or reinstalling the fuel pump.

Because degraded fuel pulse dampener seals may also have contaminated the inline fuel filter, change the inline fuel filter whenever replacing a fuel pulse dampener with degraded (orange) seals.

Evacuate, flush and clean fuel tank.

Part Part Number ---- ----------- Fuel Pulse Dampener 25029526 (With Viton Seals)

Fuel Pump Strainer 25121637

Inline Fuel Filter (GF583) 25121537

For vehicles repaired under warranty use:

Labour Time: 1.5 Hrs.

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.