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View Full Version : Troubleshooting 91 PCM ignition



goat_cheeser
09-21-2003, 05:09 PM
Looking for suggestions:

Situation: For the past 3 years, the boat has had problems starting. It will crank but the motor will not fire. We were jiggling the wire harness to get rid of the idiot buzzer and the motor would start sometimes. The motor is a PCM with the engine management system. I followed the troubleshooting guide and found the oil pressure sensor is bad. Unfortunately, the coil/computer might also be bad.

(FYI - the PCM has duplicate sensors/sending units. The sending units are for the instrumentation and the sensors are for the solid state ignition controls. You can not assume that the value shown on your gauges is the same being used by your ignition control system!)

Problem 1: Does anyone know a good source for PCM parts near Sonora, CA or Stockton/Modesto? I need to buy a replacement oil pressure sensor (not the sending unit). If not, does anyone know the specs for the oil pressure sensor so I can find a suitable replacement? (Hopefully, it is not an unobtanium part...)

Problem 2: How do I determine if the coil/computer is also bad? I checked the resistance of what I believe were the coil mounting studs to ground and had a connection. They were supposed to have infinite resistance.

Any help would be appreciated before I turn her into an anchor (just kidding :-O).

Thanks,
Jamie