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  #1   IP: 204.157.20.46
Old 10-10-2004, 07:24 PM
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No spark when I crank

Would a bad condenser account for no spark in the wire that leads from the center of the coil to the center of the distributor? Leaving this wire in the center of the coil, I've disconnected it from the center of the distributor and placed it 1/8" away from the block. There is no spark when I crank. So I think the coil is not producing any voltage, and yet I just replaced it. I've also tested the wire from the ignition switch to the pos terminal on the coil, and it has continuity and juice. I've just about given up. What am I overlooking?
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  #2   IP: 204.157.20.46
Old 10-10-2004, 07:25 PM
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Don Moyer Don Moyer is offline
 
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A defective condenser will cause a weaker spark, but it will not usually account for no spark.

The thing that you may be missing (at least in your report) is that you not only have to supply 12 volts to the positive terminal of the coil, you have to also switch the 12 volts on and off. The secondary voltage (approximately 24,000 volts) is delivered to the end of the coil lead at the instant you break the circuit through the coil. In the ignition system, the circuit to the coil is broken on the negative side by the points.

The way I like to check for coil function is to bump the starter until the points are definitely closed. Then, with the ignition switch on, I open and close the points using a pencil or small screwdriver. Each time the points open, I look for a good secondary discharge between the end of the coil lead and the top of the head.
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  #3   IP: 67.174.241.46
Old 10-15-2004, 02:29 AM
ericson_35 ericson_35 is offline
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Another idea

I recall in my final exam for my Merchant Marine engine dept. ticket (QMED)at an engineering marine school many years ago, we had various problems to deal with. One situation was an engine that would not light off as in your case. Well, after much head scratching, fiddling,and cursing, we found the devious trick; the professor took a pencil and created a carbon short circuit with a pencil between the inside coil input brass section to (I believe) another spark distributer point. SInce the carbon/graphite line was conductive yest so minute, it basically shorted the coil. We had no joy in getting the engine sparked and running until we looked EVER so closely at the distributer cap and saw the pencil mark. Doh! Sneaky b*astard!

Also, when was the last time you replaced the ignition coil and aprk plug wires? I've seen blue lighning shows under some car hoods at night due to 30 year old park plug wires.

John M.
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  #4   IP: 24.187.154.244
Old 08-27-2006, 09:54 PM
columbia28 columbia28 is offline
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Quote:
Originally Posted by Don Moyer View Post
The thing that you may be missing (at least in your report) is that you not only have to supply 12 volts to the positive terminal of the coil, you have to also switch the 12 volts on and off. The secondary voltage (approximately 24,000 volts) is delivered to the end of the coil lead at the instant you break the circuit through the coil. In the ignition system, the circuit to the coil is broken on the negative side by the points.

Don,

After not getting + to the coil I hooked up a lead directly to the + starter wire. Then I saw I was no longer getting - at the - terminal. So I hooked up another lead from the battery - to the coil - terminal. Then I tried to get spark all day to no avail. It wasn't until I read your post that I realize that hooking the - coil up to the - battery totally defeats the whole system because you can't collapse the field in the coil if its always on. I will try it the right way tomorrow and I'm really glad I read your post.
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