There is spark coming out of the coil but not out off the distributor

Tiny
MANDOCJ7
  • MEMBER
  • 1984 JEEP CJ7
  • 4.2L
  • 6 CYL
  • 4WD
  • MANUAL
  • 81,000 MILES
I had it park for close to a year I got it running and everything is restored new working. So as I was saying I got it running and it started up fine. I was using it for a week then it’s just shut off on me. So I have spark coming out of the coil but not out off the distributor there is no spark. I tested the spark plug, I grounded it and nothing. Well, I did see a little spark but then after that nothing. I already replaced the ignition control module since this was not the first time something like this happen. Now I’m a little confused hope you could help. My next step is possible replacing the distributor.
Monday, August 26th, 2019 AT 8:27 PM

8 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Hi,

If you have voltage coming out of the coil then it is possible the trigger wheel inside the distributor has failed. Take a look at the attached documents for more detail.

The only thing I am concerned with is the fact that you said you had a spark but it was weak and then you had none. If this is the case, the coil could be the issue. The coil takes the spark and changes it into high voltage on the secondary windings so if you have a weak spark, it is possible that the coil is the issue.

I would check the resistance of the coil before you replace the distributor. Connect your volt meter to the positive terminal of the coil and to the output terminal of the coil that goes to the distributor. Tell me what the resistance is and we can go from there.

Let me know if you have questions.
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Tuesday, August 27th, 2019 AT 4:36 PM
Tiny
MANDOCJ7
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Thanks for answering. I will check the coil now.
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Tuesday, August 27th, 2019 AT 5:21 PM
Tiny
MANDOCJ7
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  • 36 POSTS
Plus the trigger wheel inside looks like a little rusty.
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Tuesday, August 27th, 2019 AT 5:22 PM
Tiny
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8.96
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Tuesday, August 27th, 2019 AT 5:31 PM
Tiny
MANDOCJ7
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The coil got tested and it’s good. I took it to AutoZone.
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Tuesday, August 27th, 2019 AT 5:31 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. Then more than likely the distributor is the issue. If you have power coming from the coil which is good, and the control module is new, the only thing left is the distributor that would make sense.

Let me know what happens. Thanks
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Tuesday, August 27th, 2019 AT 5:54 PM
Tiny
MANDOCJ7
  • MEMBER
  • 36 POSTS
I have a question, in the coil side I have a red and a green should one of them be pulsing when cranking the engine over?
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Wednesday, August 28th, 2019 AT 6:46 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
No. It should not be pulsing at least not that you will visually see. You can monitor the ignition pulses with a lab scope but this get down to milliseconds.

The coil provides a voltage source for the control unit to send to the distributor. The rotor inside the distributor spins and delivers the spark to the correct spark plug. Looks like the red wire is your 12 volt feed from the ignition switch, then this actually splices off and sends 12 volts to the starter as well. The green wire goes to the ignition control module and this should be the high voltage side that gets sent to the distributor from the control unit.

Also, the control module interrupts the current field which causes it to collapse and this creates the spike for the high voltage.

What readings are you getting on both wires while cranking?
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Wednesday, August 28th, 2019 AT 7:01 PM

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