bad coil?

K

KJM

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i read the the sticky on top about trouble shooting a no spark situation and according to that i have a bad coil. i have continuity between the small pos and neg but nothing between the larger center plug in and either the pos or neg. that means bad coil? also i was wondering why this coil thats only about 2 years old would be bad so quick. i tested the ohms between the main engine haness plug to the coil and the other end at the coil while unhooked from the coil and get about 2.4 to 2.6 ohms. is this enough to be an external resister wire? the wire to the neg terminal to the main plug read about 1.4. when i test for voltage at the pos terminal of the coil i get about 11.5, is this too much? i
 
Scott Danforth

Scott Danforth

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you should have between 9000 and 12000 ohms of resistance between the secondary output and ground. nothing between the secondary and +.

I seriously doubt its the coil.

with +12 volt to the + side of coil, take a jumper wire and rapidly connect and disconnect the - side of the coil with a spark tester (or your buddy) attached to the secondary (coil tower) if your buddy sluggs you, its not the coil

since you have points, did you service the points?
 
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stonyloam

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Another way is to take the distributor cap off, put a piece of insulating material between the points, lay the center wire from the coil about 1/4 inch from the block. Turn on the ignition and with a short piece of insulated wire quickly jumper across the points. Every time you remove the jumper you should get a spark from the center wire. I also doubt it is the coil.
 
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KJM

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Scott Danforth said:
you should have between 9000 and 12000 ohms of resistance between the secondary output and ground. nothing between the secondary and +.

I seriously doubt its the coil.

with +12 volt to the + side of coil, take a jumper wire and rapidly connect and disconnect the - side of the coil with a spark tester (or your buddy) attached to the secondary (coil tower) if your buddy sluggs you, its not the coil

since you have points, did you service the points?
Click to expand...

i didn't service them but i removed the distributer and the points were as clean and shiny as the day i put them there, also only about 2 years, same time as the coil. what about the resistor wire, any idea if that is the right ohm reading? in the mean time i put a srewdriver into coil tower outlet and held the side close the engine body while someone cranked and there was no spark. i also held the connected spark plug in my bare hand while cranking and no shock.
 
Scott Danforth

Scott Danforth

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you have to re-file points after they sit for more than 90 days. they corrode over and dont make contact

verify with a dwell meter

with 12 volts on the + side, hold on to the spark plug wire while repeatedly grounding the negative side of the coil....
 
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Benny67

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Scott Danforth said:
​with 12 volts on the + side, hold on to the spark plug wire while repeatedly grounding the negative side of the coil....
Click to expand...

don't do that unless you want to get a nice jolt.

Take the coil out of circuit and measure the resistance. It should be a few ohms (2 to 6)

That doesn't mean it's good under load...but at least you can see if it's completely shot or not.
 
Scott Danforth

Scott Danforth

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the OP has already measured resistance. coil is fine.

problem with points is that when they sit, a thin layer of oxide forms
 
K

KJM

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tried a new coil and still nothing. put the old coil back on. just to be sure i have this wired right,,,,,i have a white and a tan wire joined to a tab that has battery voltage and this is attached to the small pos terminal. there are two dark brown wires attached to another tab and this is attached to the neg terminal (the shift interupter wire i believe), also there is a small black wire that comes from the distributor that is also attached to the neg terminal. is that correct?
 
Bondo

Bondo

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also there is a small black wire that comes from the distributor that is also attached to the neg terminal.
Click to expand...

Naw,...... It "Goes To" the distributor, where the points live, that fire off the coil,....
The coil's Switch,..... from there' it's to ground(-),.....
 
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Benny67

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Out of curiosity, did you look to see if the distributor and rotor are okay?

sometimes the center connection can fall out of the distributor or maybe the rotor isn't in or has a broken conductor.

​​​​​​Happens to the best of us sometimes

​​​
 
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KJM

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to be honest i didnt properly understand how the whole points ignition works until last night when i took a crash internet course. i only checked the underside of the distributor where the rotor contacts the wires contacts. i haven't removed the rotor and looked underneath at the contacts under there. i,m hoping to do that this evening and if i,m lucky i,ll find the source of my problem.
 
K

KJM

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Problem solved. It was the points. Cleaned them good and she started no problem. Should have listened to the good advise i got from the start. Lession learned, and thanks to all for the help.
 
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