| Re: [GMCnet] 2nd last cylinder doesn't receive spark [message #324906 is a reply to message #324898] |
Fri, 13 October 2017 12:15   |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
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Peer Oliver Schmidt wrote on Fri, 13 October 2017 10:12My '73 isn't running happily.
Replaced spark plugs, didn't change things.
Replaced distributor cap, didn't change things.
Went ahead, and took each of the plug wires, plug an external spark plug into it. 6 of 8 cylinders produce a spark. The 2nd last on both sides do not, i.e. 5 and 6 if you count from the left top.
Changed distributor caps. Issue remains in 5 (and 6).
Switched cables between 5 and 7, the issue remains in 5.
I am out of ideas, and appreciate feedback from the combined GMCnet wisdom 
Thanks
--
Best regards
Peer Oliver Schmidt
Peer,
Ready for a Way Out test??
When you have the cap off you can see the ring that was added with the install of the Pertronix 1181. Take a small steel something, (I used a small screwdriver) and run it around the under surface of that ring. It should try to stick to 8 places on the way around. If it does not, there is your problem.
While I have never had a Pertronix module fail, I did discover a missing magnet in a ring/rotor just once.
We started that diagnostic by pulling the wire out of the cap and cranking and one in the party noticed a missing spark. (Unfortunately, I can't claim that one.) I was looking and thought it looked good. The above test found the issue.
Other than that, I would be testing wires. That takes a VOM that can read megohms.
Please let us know when you find it.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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