REDUCTION IN PERFORMANCE ON WARM-UP OR HOT ENGINE

VEHICLES AFFECTED: 1983 Thru 1985 'F' Series

Some 1983 thru 1985 'F' Series may experience a reduction in engine performance or sag under normal acceleration. This condition occurs during engine warm-up or occurs with a hot engine.

To repair this condition, check for proper THERMAC operation as shown in Section 6E1 of the appropriate Service Manual. If proper performance of the THERMAC is confirmed, refer to bulletin 84-6-233 for the fuel vapour lock kit in Step No. 7.

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.