'79 ford spark problems
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'79 ford spark problems
hello, this is my first post on this forum. I have a '79 f100 with a 390 from a '69 Galaxy. For some strange reason, I cant get spark from three of the plug wires. This is after replacing the plugs, wires, distrubutor, coil, and swapping out for an electronic ignition. it was running ok prior to installing the new ignition. The engine is so simple, and I've replaced so many componants that I cant think of what else it would be. Any advice would be greatly appreciated,
thanks,
-Luke
thanks,
-Luke
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Joined: Apr 2009
Posts: 14,333
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From: Stanley, VA
What type of electronic ignition did you install? Dura-spark or sftermarket?
Which three cylinders aren't firing?
When you say you can't get spark from three of the plug wires, how are you checking for spark?
Did you try going back to the original ignition to see if it starts running okay?
BTW, welcome to FTE. Lot's of good, knowledgeable people here.
Which three cylinders aren't firing?
When you say you can't get spark from three of the plug wires, how are you checking for spark?
Did you try going back to the original ignition to see if it starts running okay?
BTW, welcome to FTE. Lot's of good, knowledgeable people here.
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It's an Ignitor electronic ignition. I discovered that if i rotate magnetic sleeve 90 degrees on the distributor shaft, it causes three other wires not to have spark so im assuming the sleeve was bad right out of the box. I put the points back in and it wouldnt even run long enough for me to check the spark. after putting in a new condensor (third new one) it runs fine. I had to put in a new condensor about a week ago and it left me where I am today. So i guess my question now is, why am i frying my condensors? should I go with electronic ignition again or will it be just as bad as this one? and I check spark with a timing light. thanks, -Luke
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Joined: Jul 2013
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From: Southern Kentucky
Ive had a bad ignition control module be bad brand new out of the box and a brand new coil fail in just two weeks. This all happened this month and I quit buying cheap parts from auto part store chains an will only use NAAPS
Freshman User
Joined: Jul 2013
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From: Southern Kentucky
Ive had an ignition control module be bad brand new out of the box and a brand new coil fail in just two weeks. This all happened this month and I quit buying cheap parts from auto part store chains an will only use NAPA or Ford from now on...do NOT trust "new" parts from chain stores
MSEE
Joined: Apr 2004
Posts: 10,386
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From: Austin, TX
This is an aftermarket Ignitor upgrade, not factory electronic ignition.
High primary current is one possible explanation for continuously frying condensers. A higher primary current leads to a higher primary voltage "kick" when the points open. One possible explanation for high primary current is the absence of a ballast resistor.
The condenser can also "go bad" if the ground clip breaks off, which happened to me once. Are you under the impression that you're frying condensers because replacing the condenser alleviates the problem? The next time you suspect the condenser, remove it, temporarily short the signal lead to the condenser body, remove the short, then ohm the condenser out. You should see it initially register as a short, then turn to an open circuit. If you read a static resistance, then the condenser has failed. Another possibility is that the condenser is fine, but you have an issue with the points or breaker plate, and the act of working in the distributor is what's actually fixing a different problem. That, or there's more to the story.
High primary current is one possible explanation for continuously frying condensers. A higher primary current leads to a higher primary voltage "kick" when the points open. One possible explanation for high primary current is the absence of a ballast resistor.
The condenser can also "go bad" if the ground clip breaks off, which happened to me once. Are you under the impression that you're frying condensers because replacing the condenser alleviates the problem? The next time you suspect the condenser, remove it, temporarily short the signal lead to the condenser body, remove the short, then ohm the condenser out. You should see it initially register as a short, then turn to an open circuit. If you read a static resistance, then the condenser has failed. Another possibility is that the condenser is fine, but you have an issue with the points or breaker plate, and the act of working in the distributor is what's actually fixing a different problem. That, or there's more to the story.
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don_79f250
1973 - 1979 F-100 & Larger F-Series Trucks
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Jun 14, 2004 01:38 PM
