1991 Oldsmobile Cutlass Ciera No Start

1991 OLDSMOBILE
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ELPRUP
  • MEMBER
  • 2 POSTS
3.3 V6, but that shouldn't matter...

The car quit while driving. It will crank, but not start. I believe it is the ECM because when it quit, then speedometer also dropped to zero. If this didn't happen, I would have suspected fuel or ignition. I want to confirm that it is most likely a bad ECM.

The ECM and other fuses in the fuse panel are okay. The fuel pump doesn't prime when the ignition is turned on (bad ECM's fault?). The initial dash lights do come on when the iginition is first turned on (not under of the ECM's control?)

I haven't checked for spark or fuel, but I'm hoping that the speedometer going to zero at the same time it quit specifically narrows the issue down to a bad ECM. If my assumption is correct, can I get away with changing a relay or should I just swap the whole ECM? I can get an ECM for $40. How much is the relay? The only problem is that I fear the ECM I'd be getting isn't KNOWN to be a working unit.

If my assumption is confirmed, then it will do two things for me. First, it would tell me that I wouldn't be wasting $40 for nothing. This part isn't really a big deal; I'm willing to risk $40. The second thing is that if the speedometer going to zero when it quit specifically means that it is my ECM, then I'd know that the ECM I swapped in was also a bad one if my car didn't start after the swap.

Thanks for your help.
Feb 21, 2007 at 3:52 AM
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CHEVY22
  • ✓Experienced Mechanic
  • 1,375 POSTS
there are alot of things this could be , i never suspect and ecm,pcm vcm or tcm until i have checked everything else , your gonna have to dig in and do some testing , check the f/p relay if that is ok check for power at pump should shoot 12v for 2 seconds and work from there ,but like i said there are 100 things it could be , ecm needs input signals to start and run the engine and if it loses one bam, start simple , fuel , fire
Feb 21, 2007 at 3:58 AM

Suggested Repair

Do not replace the ECM first. Check the fuel pump relay, confirm the pump receives about 12 volts for roughly two seconds when the ignition is turned on, and verify fuel and spark before considering an ECM swap.

Conversation Summary

A 1991 Oldsmobile Cutlass Ciera with a 3.3 V6 quit while driving, cranks but will not start, and the speedometer dropped to zero. The owner suspects the ECM because the fuel pump does not prime, although the fuses and initial dash lights are okay. The expert says an ECM should not be assumed until simpler checks are done, including the fuel pump relay, power at the pump, fuel, and spark, because many lost inputs can prevent starting.

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