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Discussion Starter · #1 ·
I got the carburetor worked out but I have no spark.
Can someone please walk me through the troubleshooting routine?
I cleaned the points and they appear to be opening and closing. Gap set at .020.
New spark plug.
Coil ohms read the same as a new coil.
I have 12.5 volts power to the positive terminal on the coil, and the same at the negative terminal.
A test light stays on at the negative coil terminal when I crank the engine. I expected it to go on and off.
The wire from the negative coil terminal to the points has only minimal resistance from one end to the other.
I'd start over from scratch if someone will post a logical sequence.
I need this tractor running, to push snow.
Thanks!
 

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Here is a basic diagram for a points ignition circuit:
1. Check your grounds and battery terminals.
2. You said you had voltage at the coil +; that would be the ignition side of the coil. You should also have + 12.5 v at the point's arm. Current flows thru the points to ground when the points are closed and a magnetic field builds up in the coil. When the points open, the field collapses, inducing a higher voltage in the secondary.
3. Did you check the resistance of the secondary coil? The resistance of both coils - primary and secondary should be fairly low.
4. Your spark plugs are clean and properly gapped?
5. If the coil is good, primary and secondary, you should get a spark at the grounded spark plug by manually opening the points with the ignition switch on (and motor, of course, not running).
 

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"A test light stays on at the negative coil terminal when I crank the engine. I expected it to go on and off." I agree! Something is going on with the points, maybe not closing, possibly wire from coil to points broken or bad connection to points. Not sure what condenser will do here, but I'd disconnect for troubleshooting.

You said points "appear" to be closing. Remove wire from coil and verify connection to ground with points closed.

As another thought, a bad/shorted condenser would act the same as the points never opening and voltage would never be induced into secondary windings, so all the more reason to disconnect for test purposes! Bob
 
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Discussion Starter · #4 ·
"A test light stays on at the negative coil terminal when I crank the engine. I expected it to go on and off." I agree! Something is going on with the points, maybe not closing, possibly wire from coil to points broken or bad connection to points. Not sure what condenser will do here, but I'd disconnect for troubleshooting.

You said points "appear" to be closing. Remove wire from coil and verify connection to ground with points closed.

As another thought, a bad/shorted condenser would act the same as the points never opening and voltage would never be induced into secondary windings, so all the more reason to disconnect for test purposes! Bob
My brand-new Kohler branded points would not conduct electricity. I finally went back to basics and used my multimeter.
A couple of swipes with emery cloth an a follow up swipe with a shop rag fixed that. The old points would not conduct electricity even after a few emery cloth treatments.

I got it started this afternoon late. The spark tester lit up on the first revolution, and then the engine started on the second revolution. Tomorrow I can adjust the carburetor and put the hood and engine covers back on the tractor. When it snows I will be able to clear the long gravel and the short steep concrete driveways.
 

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My brand-new Kohler branded points would not conduct electricity. I finally went back to basics and used my multimeter.
A couple of swipes with emery cloth an a follow up swipe with a shop rag fixed that. The old points would not conduct electricity even after a few emery cloth treatments.

I got it started this afternoon late. The spark tester lit up on the first revolution, and then the engine started on the second revolution. Tomorrow I can adjust the carburetor and put the hood and engine covers back on the tractor. When it snows I will be able to clear the long gravel and the short steep concrete driveways.
Glad you got it running. I'd suggest you take those old points, and carefully clean up the contact surfaces with very fine sandpaper - 500 wet-or-dry or finer. If the rubbing block is not damaged, these can be a spare pair after you test them with your meter. Use one probe on the spring, the other probe on the contact point. Unless there is rust or corrosion, you should be able to clean them up.
 

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Discussion Starter · #7 ·
Glad you got it running. I'd suggest you take those old points, and carefully clean up the contact surfaces with very fine sandpaper - 500 wet-or-dry or finer. If the rubbing block is not damaged, these can be a spare pair after you test them with your meter. Use one probe on the spring, the other probe on the contact point. Unless there is rust or corrosion, you should be able to clean them up.
I've actually done that already and they failed again. The points - the contact areas - are shiny. They still will not conduct electricity. I bought a very expensive set from the NAPA store to be my backup.
 

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I've actually done that already and they failed again. The points - the contact areas - are shiny. They still will not conduct electricity. I bought a very expensive set from the NAPA store to be my backup.
They are metal, how could they not? I don't doubt you have it right, but how can that be? Something is wrong with the points, but where is the break in the conductive path?

I would check continuity from the spring strap to the contact point on that piece. Then I would check the same from the frame to the contact point on the mate. With the pieces still on my bench, I'd clamp them together with a clothes pin or rubber band and test for continuity from the spring, thru the two points to the frame on the far side. Might the points be some hard insulating material that is plated and the plating is worn away?

I assume they were adjusted properly in the distributor and the rubbing block was not too long and that kept the points open.
 

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Discussion Starter · #9 ·
I ran through all of those possibilities, and finally gave up. My conclusion was that there was something in the set that prevented them from working but I had run out of time and patience. I'm getting too old and impatient.
 
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