TO-20 Runs and Stalls

Here's the deal: Was given a '51 TO-20 that sat unused for maybe 2-3 years. Replaced the coil, rebuilt the distributor, replaced the fuel line and filter (routed away from the manifold to prevent vapor lock), rebuilt and thoroughly cleaned the carb (8-10 times now), replaced the entire coolant system, flushed the tank, replaced the sediment gasket and filter, etc., etc. Tractor starts effortlessly and idles smoothly, with excellent throttle response in all ranges. No misses, no backfires, just hums right along.

Once I start driving around, it runs perfectly for just a couple minutes and then cuts out. Will sometimes re-start and run for another minute or so before eventually dying completely. Have checked (and rechecked) fuel flows and it's good all the way through. Am definitely getting good spark as evidenced by the smooth running on all cylinders.

I'm at my wits end with this thing. Would greatly appreciate any insights. As often as this problem is listed here, surely someone has figured it out by now.

Anyone?

Turns out it was either the ignition switch (which looked pretty damned ratty when I pulled it) or the coil (which was not the right one for this tractor). Replaced both this morning and she fired right up and ran like a champ. Finally....

Can thank you all enough for your help.

I picked up a new coil (NAPA IC-14SB; had to send the knucklehead at the counter back twice when he brought me the wrong ones even after I gave him the part number on a piece of paper) and a new 20a switch yesterday. Will try those solutions tomorrow. Also suspect of the aforementioned connection between the coil and the distributor; as I recall it is probably the original cloth-covered wire from the 50's. Will replace it as well.

Thanks again for all the assistance. I'll keep you all posted.

This is a Ford 8N "Side mount" Flow chart but it should work on your Tractor.

Voltage Measurements are in upper left

I would guess that the small WIRE from Coil to Points is shorting where it enters the side of the Distributor. Shake the sucker!

Hope This Helps

If I were you when the problem occured, I would immediately check the SPARK AND THE FUEL DELIVERY. That would give you a starting point.

My gut feel is that you are having an ignition problem BUT I NEVER ASSUME ANYTHING IF I DON'T HAVE TO! You could have the vent plugging in the fuel cap which allows fuel delivery for awhile and then restricts it. So check the vent in the gas cap.

You didn't say what electrical system you have (6V OEM or 12V conversion). There are usually two things that cause the problem you are seing. One, as Phil has pointed out is a bad ignition switch which get a high resitance in about 10-15 minutes or an overheated coil which usually takes much longer to overheat.

The former can be checked by putting a jumper across the switch and seeing if that improves the situation. If it does, replace the ignition switch.

IF you have a 12 V electrical system, make sure that you have a real 12V coil, not the 12 V coil that has the tiny writing on it that says it must be used with an external resistor. If you have one of those and you didn't put the required resistor in series with it, you could be overheating the coil. Or if you have a 6 v coil on a 12 V sytem, the same is true. If you have acoil AND the resistor, when this occurs check the continuity across the resistor and see if it's failing in that mode.

Finally don't conclude from smooth running, that you must have a good spark. Check it out! It takes less than 2 minutes and it's gotta' be FAT, AND BLUISH-WHITE!

When it idles and won't run long under load that still sounds a lot like a fuel flow problem because a coil heating up should heat the same at slow or high speed so it should have troubles at about the same time whether idling or running hard. A condenser may fail faster running fast, but my condensers usually don't recover from a failure.

You might check for fuel level by screwing in a hose barb fitting in place of the float bowl drain plug and then run a piece of clear plastic tubing to the side and up so you can have a gas level guage and see if its holding up when running hard.

Gerald J.

First the coil. Can someone please provide a part number for the appropriate coil? I'll pick one up and try that as a solution. Not certain of the coil as it was given to me as NOS parts with the tractor. Could be bad.

As for the ignition switch, there's no keyed switch on the tractor; just a toggle switch that completes the electrical circuit. Definitely could be the culprit as it too was a NOS gimme. What are the appropriate specs on the switch I need. I'll replace it as well and see what I get.

Again- many thanks to all. What an excellent resource this board is.

The ignition switch needs to carry 8 or 10 amps, 15 or 20 if the lights are on it too.

A universal keyed ignition switch will carry the current and isn't expensive. Nor will it last forever. Mine failed just like your symptoms, a new switch and tightened up wiring connections cured most all those problems. I still need to clean up the connections at the transmission safety switch.

Gerald J.