1987 Pontiac Bonneville No Spark

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BOEING727
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  • 2 POSTS
help !
This car was in storage and has 20,000 miles on it....occasionally will not start.Was towed to a GM garage..and started immediately off of the hook. The shop was perplexed and did nothing.
But this "fault" is continuous and without rational explantion.
Recently it just quit while driving.....started 10 minutes later.
As of 4-10 ....it simply will not fire.
We've found, over time, that cycling the shift handle seems to reset something ....but this time...no 'at-home' tricks seem to work.
No apparent spark to the plugs (4-10) ....but why? What am I missing...and why the occasional restart without doing anything?
Note: it's a local driver only (thank God)....but is now quickly becoming a large headache.
Any suggestions before I put it on the hook again?

Thanks --
Apr 10, 2006 at 7:40 AM
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LOSONE
  • ✓Experienced Mechanic
  • 1,616 POSTS
How long in storage?? Sounds like a bad ignition module. If in storage over 12 months the fuel is contaminated. Let me know
Apr 10, 2006 at 10:50 AM
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BOEING727
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I'm now being told it seems to be the crank angle sensor........
contaminated fuel is out of the question as the car has run through many miles since removal from storage.

My only remaining question,assuming the crank sensor is nothing but conjecture.....is "what if"....if could then be the ECM.....or hundreds of bucks in yet another direction !~

Thanks for your suggestion ref fuel . I appreciate it.
Apr 11, 2006 at 10:22 AM
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LOSONE
  • ✓Experienced Mechanic
  • 1,616 POSTS
The crank sensor is behind the harmonic balancer. It is sometimes damaged by dirt. The balancer is easy to take off with access by removing a panel in the fender well. Be careful when removing and replacing because the sensor fits between two plates on the balancer. Not a bad thought.
Apr 11, 2006 at 12:49 PM

Suggested Repair

Inspect the crank angle sensor behind the harmonic balancer, which can be damaged by dirt; access it by removing the fender-well panel and take care because the sensor sits between two balancer plates. Also consider a failing ignition module given the intermittent no-spark and no-start.

Conversation Summary

A 1987 Pontiac Bonneville with low mileage intermittently fails to start, sometimes dies while driving, and later shows no spark. Cycling the shifter sometimes seemed to reset it, but that no longer works. A shop could not reproduce the fault. The owner ruled out contaminated fuel after many miles of driving. An expert suggested a bad ignition module and agreed the crank sensor behind the harmonic balancer is a reasonable check.

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