FAULTY TBI DIAGNOSIS & REPAIR TEST PROCEDURES

1987 SUNBIRD MODELS EQUIPPED WITH 2.OL LT2 ENGINE (VIN CODE K)

If an engine problem has already been identified to be a faulty TBI injector, further investigation is required.

Besides dirt in the injector, the injector may have overheated via a longer than normal 12 volt signal, i.e., a grounded harness or ECM.

If the failed injector's electrical resistance is less than 1.5 OHMS or infinity (1987 only) , then injector grounding is probable.

An external injector harness ground can be checked by performing an engine off continuity test of the injector harness to ground. Any grounds should be eliminated.

An internally grounded ECM will not generate any diagnostic codes. However, an ECM box with a round sticker, silver background and blue letters of the Delco Electronics logo may develop an internal ground. Therefore, the ECM should be replaced when both the injectors - resistance indicate grounding and no harness grounds exist.

The ECM replacement is the only way to insure no future injector failures for the customer with this specific ECM.

SERVICE DEPARTMENT PONTIAC DIVISION GENERAL MOTORS CORPORATION

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.