SH not sparking.

GordoSD · May 22, 2012

54 Farmall SH. Will crank fast but no spark at plug. Have 6 volts at both coil terminals, and 6v at side distributor lug.
Replaced condensor, points, rotor and cap.
Can't see any spark at points but is this normal for bright light (tractor is outside) and 72 year old eyes? What other trouble shooting to get spark at plugs.
Don't know if this makes a difference but the ignition switch was left on since last November and the battery was fully charged. Couldn't believe it when I found that switch on and the battery waas good.

The Red · May 22, 2012

Sounds like a bad coil switch. I guarantee you that battery would have run down in less than a day if the switch was on and operational. Take a wire and check each side of the coil switch and see if you can spark it against the frame.

old · May 22, 2012

I do not believe I am doing this LOL. New condenser could be bad or when you installed the points you got the wire hooked up in such a way it is shorted out BTDT on a 450 once. Or the insulator going threw the side of the distributor is bad and is shorting out so no power to the points. Get some shade some how on the distributor side of the tractor and take the ignition side of the distributor wire off and with the key on watch for sparks when you touch that wire to the coil. If you have spark and the points are open you have a short.

James Williams · May 22, 2012

New points are famous for not firing,need to take a small file and scrape them

jimmy

Bob M · May 22, 2012

Something's wrong with the points!

With the engine stopped in a "normal" crankshaft stopping position (ie. with the points closed) and the ign switch "on" you should see 6 volts at one coil terminal (the one wired to the ign switch) and 0 volts at the other. You should also see 0 volts at the distributor side lug.

But since you are getting 6 volts at both places it means the points are not grounding when closed. Try lightly filing or running abrasive cloth through points to clean them up, then regap them to 0.020.

If that doesn't get you a spark, replace the points.

teddy52food · May 22, 2012

Must have stopped with the points open. Clean them up good to get them to contact again.

John T · May 22, 2012

I agree with Bob M.....Since the engine dont tend to stop on the TDC of a piston under compression, the points are usually closed, they open at TDC of a piston to fire that pistons plug THEREFORE with the ignition on and her just sittin there Id expect 6 volts on the coils LV primary input BUT ZERO VOLTS (with respect to ground) on the output where the coils LV primary output wires to the distributor.

If not, the points arent closing or arent wired right or the wires bad from coil to distributor or the distributor or points arent getting a good ground. Check the wire inside the distributor from the points terminal to the pass through stud where the coil wires !!!!!!!!!!!!!!

The coil cant ever conduct current until the points are closed and the to ground circuit (via points) is complete,,,,,,,,,,that means a test lamp on the coils LV primary output should go OUT when poinst are closed as that becomes ground

Run my Troubleshooting Procedure for more detail..

John T
John Ts Ignition Troubleshooting

David G · May 22, 2012

You have an open circuit in the points if both sides of the coil always have 6V. The coil should have 0V on the distributor side when the points are closed.

Are you sure you gapped them right?

Janicholson · May 22, 2012

With respect, it was on for several months with no discharge, the points are open to ground, either they are not closing at all, or they are not actually connected to the terminal. Corosion inhibitor on the points could be insulating them as well. A test light inside the distributor will probe out the issue rapidly. Jim

GordoSD · May 23, 2012

Got a good look in the predawn at the "no spark" areas and confirmed them. Put a pipe wrench on the crank rod and turned it slowly, sure enough points were no opening. Opened them, sanded them with a little point stick I got from Grandpa 60 years ago, adjusted to 20 and had good plug spark.
Turned her over a dozen times and no start. Pulled a plug and it seemed kinds dry. That good habit of turning off the fuel after ahutting down..oooops.
Opened the fuel petcock and it fired after 1 turn.
Thanks to all, especially Rich, for chiming in.

SH not sparking.

GordoSD

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The Red

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old

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James Williams

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Bob M

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teddy52food

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John T

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David G

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Janicholson

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GordoSD

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