400 no start update

super99 · Oct 17, 2016

Is there any way to check a condenser? I stopped at Napa after work and got a tune up kit for IH 12 volts thru 1958. I changed the points and condenser, dropped the brass screw for the points in the grass and couldn't find it, had to go steal a screw out of the JD 70 distributer to get them put in. Still no fire. I pulled the coil wire and laid it against the loader frame and cranked it over and it has spark there. Power to the resistor, test light lights up on the stud thru the side of the distributer. Did I get a bad condenser? I have had new ones that were bad before, maybe again?? What else to try?? Thanks, Chris

GordoSD · Oct 17, 2016

try holding a plug in a wire held tight against the tractor frame. Should get a fat blue sprk. Do it after sunset or inside with lights off.

Janicholson · Oct 17, 2016

if you are getting spark from the coil to the block, the rotor or cap has a track/crack or hole to ground. Jim

JD Seller · Oct 17, 2016

Try a different rotor button and then a cap. You say your getting spark from the coil wire. So your points and condenser are working. Your not getting spark up through the cap/rotor button.

I have a rotor button in my tool box that has less than two hours on it. It looks perfect too. It will not fire a spark plug. I did a tune up on a customers tractor. He called me later the next day and told me the tractor just died like you shut the key off. I had fire at the coil but not at the plugs. I still had the old cap and button with me. I tied the cap first, still no go. Switch the rotor button and it took right off. switch the cap back and it ran fine. Put the "new" button back on and it would not run. The funny thing is the rotor button checks out fine with a volt/ohmmeter. The only thing I can figure out is it allows the high voltage spark to jump to the distributor shaft.

So try the rotor button first and then the cap.

John T · Oct 18, 2016

If the coil wire is firing strong to ground but none at any spark plug THE PROBLEM IS THE DISTRIBUTOR CAP OR ROTOR NOT CONDENSOR. I have seen rotor tips that have a short to the end of the dist shaft where they snap fit down so no fire gets out the tip to the cap. I have seen wrong dist caps that still fit as the problem. I have seen dist caps with hairline cracks or carbon traces that short the spark to ground versus delivering it to the cap where it should go. I have seen caps where the carbon at top the rotor springs against is bad.

YES a real capacitor tester can check a condenser and even a voltmeter using the kickback test can provide some indication but if you have a good spark out the coil that's NOT the problem, dist cap or rotor tip is where Id be looking.

John T

John T · Oct 18, 2016

JD, a low voltage ohm meter or continuity tester etc. can easily show all is good and continuous or open, BUT THAT DONT MEAN IT WONT BREAKDOWN WHEN MAYBE 10,000 VOLTS IS PRESENT. A device can show fine when only a few volts is applied (like an ohm meter) but put high voltage across the same location and you can get HV breakdown and that's common like in dist caps or rotor tips where a hairline crack or carbon trace allows a HV arc.

Hope this helps

John T

400 no start update

super99

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GordoSD

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Janicholson

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JD Seller

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John T

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John T

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