HOT WEATHER DRIVEABILITY (INSTALL NEW FUEL SENDER/PUMP)

SUBJECT: HOT WEATHER DRIVEABILITY (INSTALL NEW FUEL SENDER AND PUMP ASSEMBLY)

VEHICLES AFFECTED: 1991-92 "F" CAR WITH 5.OL TBI ENGINE (RPO L03)

CONDITION:

--------- Some 1991-92 F-cars with 5.OL TBI engine (RPO L03) may exhibit a hesitation/stall during an aggressive stop that may result in a prolonged/hard restart. This condition has only been experienced during high ambient temperatures when the fuel gage reads one half full or less.

CAUSE:

----- The TBI fuel pump is ingesting air/fuel vapors when fuel is sloshed away from the fuel pump pick-up strainer.

CORRECTION:

---------- Follow appropriate Service Manual procedures when diagnosing fuel-related problems. When the above symptoms are present, verify the condition by checking the fuel system pressure for pressure loss during an aggressive stop above 56 km/hr (35 mph.)

If diagnosis indicates fuel pressure loss, a possible cause is the fuel pump losing prime. Vehicles may be repaired by replacing existing Fuel Sender and Pump Assembly with new assembly, P/N 25029778, with derated rollervane pump following applicable Service Manual procedures, Section 6C, Engine Fuel.

WARRANTY INFORMATION:

For vehicles repaired under warranty use:

Labor Operation: L1200

Labor Time: 2.6 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.