What do I try next?

Tiny
LVANDYKE
  • MEMBER
  • 1991 GEO STORM
  • 150,000 MILES
9 months ago replaced ecm ignition module altinator fusable link and replaced a broken coroded heavy gage wire from the altenator to fusable link. A few months ago replaced the cap and rotor when the car quit. Quit again and I get spark from the coilwire. And no spark from the plug wire. Check to see if rotor was turning, it was and I am assuming timing belt is OK. Had the ignition module checked again and it tested bad. Replaced and still no spark from the plug wire. Assumed pick up coil next. Replaced entire distributor with no luck. What is the next thing to try?
Friday, June 8th, 2012 AT 4:03 AM

5 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
Windshield wiper motor.

You have spark from the coil wire so obviously the module, pickup assembly, and coil are working. Why are you replacing those parts? First of all, what is the symptom? Do you have a no-start condition or are you fighting a misfire?

That spark from the coil wire should be blue and a good 1/4" long. If it's just a tiny spark, treat that as no spark. Sounds like you have a bad plug wire or there's a carbon track inside the new distributor cap. Bad plug wires can cause that because if the spark can't get through the plug wire, it's going to find another path to ground, and that is likely to be inside the cap.

If the spark from the coil wire is strong, instead of holding it close to a metal part of the engine, hold it close to the terminal on the distributor cap. If it's strong there, replace the cap, rotor, and plug wires.
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Friday, June 8th, 2012 AT 6:58 AM
Tiny
LVANDYKE
  • MEMBER
  • 3 POSTS
Thanks for the info. Some things are more obvious to the experts. The spark from the coil wire is blue and strong. I have a no start condition, not even a sputter. There was an occasional misfire before it just got up and quit. I don't see any carbon track in the cap, however I do see a small carbon spot on the rotor under the center contact. I will do a better check of the wires, cap and rotor. Thanks again!
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Friday, June 8th, 2012 AT 8:18 AM
Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
That carbon on the rotor is likely just ground up carbon particles from the contact on the cap. That is not desirable, but it is normal. However, that could be a clue. GM had some trouble in the '70s when they first came out with their High Energy Ignition (HEI) systems. Those were capable of producing over 45,000 volts. If a spark plug wire was removed while the engine was running or cranking, that spark WAS going to find a path to ground and it usually was through the center of the rotor to the distributor shaft. That was called "punch through", and the resulting carbon track caused the rotor to become shorted to ground and kill the spark to all the plug wires.
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Friday, June 8th, 2012 AT 8:28 AM
Tiny
LVANDYKE
  • MEMBER
  • 3 POSTS
You were right on. Upon further inspection of the rotor I did find the "punch through", just surprized that it would do that after being just 2 months old. Replaced cap and rotor again under waranty and with the mis fire after all these copmonents were replaced I replaced the wires and plugs. Mis fire went away. I am thinking you were right on the wires being the cause of all my grief. Should have started there earlier. Thanks for your suggestions!
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Saturday, June 9th, 2012 AT 6:35 AM
Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
Happy to hear you can buzz off, ... Ah, I mean SAIL off into the sunset.
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Saturday, June 9th, 2012 AT 8:58 AM

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