GM Service Manual Online
For 1990-2009 cars only

CODE 51,55;FUEL FLOW INTERRUPT POSSIBLE MISSING CALPAK

MMELS AFFECTED: 1984 SKYHAWK - 1.8L TURBO

When Codes 51 or 55 are indicated and fuel delivery to the engine is interrupted, the ECM should be checked for a missing Calpak. Code 52 will NOT register if the Calpak is missing. If the Calpak is in place, normal diagnostic should be used to check for a malfunctioning PROM or ECM.

When servicing the ECM, both the Calpak and PROM must be transferred to the new ECM.

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.