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91 gp 3.1 cranks/no start


dcpro
09-22-2006, 12:34 AM
I have 91 gp 3.1 with 71,000+ miles on it replace the fuel pump (with40+psi), crank position sensor...it cranks but no spark ........ecm shows code 12.....
ecm service @ 01227727 862491 M025702967 16152491

richtazz
09-22-2006, 06:03 AM
First you need to determine if you have spark and injector pulse when it won't start. Your problem could be an ignition module or ECM depending. Try spraying WD-40 or starting fluid in the throttle body. If the car starts, then dies, you have both, and the problem is fuel delivery (possibly bad injector[s] since your fuel pressure is good, and not likely related to either the ECM or ignition module. The ECM # you have is very problematic. You can do a "tap test" to see if the ECM has loose internal connectoins, but be GENTLE. Use only the tips of your fingers or a screwddriver handle along the top edge of the ECM and TAP (dont club it to death). If it starts before or after tapping, and then dies again if you continue tapping, the ECM is definitely bad. If you see any signs of water intrusion (swelling/separation of the case) get a new one (stay away from Cardone brand reman units, as they are problematic). You'll need a spark tester for checking spark, and a noid light for checking injector pulse. With a little effort, you CAN get to the injector harness on cylinder #6 without taking the upper plenum off to plug in the noid light. I just helped my neighbor on his 91 Lumina (mechanically identical to your car) and with the noid light determined he had no injector pulse. We replaced his ECM and he's good to go. You can take the ignition module off (not an easy task because of where it's mounted) and have it tested at Auto-Zone or Advance for free. Make sure they run the test enough times to get the ignition module warm, as they can intermittently fail due to temperature.

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