Farmall H wont start

KRS · Nov 13, 2010

I am trying to help my brother in law fix his H.
It was running good and just stopped, wont fire.
We put in new plugs, points, condenser and plug wires. Still does not fire. Tried a new coil, no change. We pulled a plug and turned it over to look for a spark. Once or twice I saw a very small spark, but when I let go of the starter there was one nice bright spark. It is a 12 volt conversion. Any advice would be appreciated.
Thanks

TomH in PA · Nov 13, 2010

How does the wiring look? It sounds like you might have a bad connection somewhere. Check each wire, loosen and clean the connections.

John T · Nov 13, 2010

Usually when a tractor is converetd 6 to 12 and the 6 volt starter still used, theres not such a drastic voltage drop while cranking so as to reduce spark energy significantly. I say that since you indicate the sparks hot when shes not cranking which sounds like a voltage drop while cranking/starter/cable issue. A faulty starter can drag the voltage down so low theres a weak spark when cranking, how well does she crank over????

Is it a 6 or 12 starter and how are the battery cables and connections and grounds??? Id remove, clean n wire brush, n reattach each n every battery n starter n ground cable and each switch connection then try her

What voltage is that new coil, 6 or 12??? Is there an external series Balalst Resistor in the primary ignition circuit???????

A weak spark is often due to burned or corroded points or a weak condensor. You might try to hot wire the coil just in case its a faulty resistive ign switch.

After cheking the coil/voltage and cables n connections and any ballast issues, heres my Ignition troubleshooting procedure.

http://www.ytmag.com/cgi-bin/viewit.cgi?bd=farmall&th=5745

John T
Ignition troubleshooting

Anonymous-0 · Nov 13, 2010

You could try hot wiring the ignition. Connect a jumper wire (preferrably fused) from the pos. post of the battery to the + terminal of the coil. This is assuming that the tractor is set up as neg. ground. If the tractor starts and runs this way, then you have bad connections, wiring or ignition switch. I've had ignition switches with bad contacts act this way.

Tom Fleming · Nov 14, 2010

If you replaced the coil, check the polarity of the electrical connections to the coil. Is the tractor still positive ground?

Brian Jasper co. Ia · Nov 14, 2010

Have your battery tested. I'll bet money it has a bad cell. With a 12V system, you need to keep cranking voltage above 9.6V for the ignition system to work. Under compression pressure, higher voltage is required to jump the same gap in open air. From your description, you probably had an ignition problem that you fixed by tuning the engine. Your starter is 6V and still works well because the voltage is staying well above 6V while cranking.

KRS · Nov 15, 2010

Thanks for the ideas.
I will be working on it this weekend.
KRS

Farmall H wont start

KRS

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TomH in PA

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John T

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Anonymous-0

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Tom Fleming

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Brian Jasper co. Ia

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KRS

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