For 1990-2009 cars

# FUEL PUMP RUN-ON AFTER ENGINE TURNED OFF

FUEL PUMP RUN-ON 1982-87 VEHICLES EQUIPPED WITH FUEL INJECTION

Some vehicles with engines equipped with Throttle-Body-Injection (TBI)or Multi-Port Fuel Injection (MPFI) fuel systems may exhibit a condition where the fuel pump continues to run for 3 to 4 seconds after the ignition is shut off.

This condition will most likely occur when a cold engine has been started, run for a very short time (oil still cold), and shut off.

This condition occurs because some engine fuel systems are wired so that when the engine oil pressure is above 4 psi, the fuel pump will continue to run via a switch in the oil pressure sensor.

Customers whose cars exhibit this condition should be assured that their vehicles are operating properly, and that the fuel control system insures that all fuel pumped to the engine after shut-off is returned to the fuel tank. NO REPAIR SHOULD BE ATTEMPTED.

If the fuel pump continues to run for significantly longer than 3 to 4 seconds after the ignition is shut off, refer to section 8A of the chassis service manual for information on diagnosis and repair/replacement of the oil pressure sensor switch.

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.