Cub Stalling

[Torson]

I have a 1947 Farmall Cub. It runs well for 20 minutes then stalls. I can start it up right away, but it stalls as soon as i engage the clutch. If I leave it alone for an hour or so, it will run again for about 20 minutes. Any ideas? Thank you.

[Don McCombs]

Likely the ignition coil is failing. When it stops running, check the coil to see if it is hot.

[Glen]

Hi,
A 1947 Cub came with a magneto. Some Cubs were changed to a Battery Ignition unit.
The magneto coil is different than a cylinder shaped car coil used in the past.
The coil is originally under the cover on top of the magneto.
Below is a listing at TM Tractor Parts, at the bottom of the page, for a new coil for the Cub magneto.
You can look at the pictures.
http://www.tmtractor.com/new/el/713fp.htm

I sent you a PM, you get to it at the top of the page.
Below are pics of where the points are, and the rotor timing marks.

[inairam]

If it starts right up after the stall then the coil does not have time to cool, if it was switched to a battery ignition.

Have you checked the fuel tank and the sediment bowl for debris? maybe replace the filter screen on top of the sediment bowl' check the screen at the inlet to the carb.

[tinnerjohn]

Sorry I'm late to this, but a thought that comes immediately to my mind is rust, dirt, whatever slowiing the fuel flow to the sediment bowl, I've had this happen a couple times, once it was old fuel cap gasket that was floating around and acting like a check valve. Might want to check the screen in the carb and maybe the carb bowl too. Best of luck to you. I know how frustrating that can be.

John

[Waif]

How hot when it stalls? Can you put your hand on the coil cover? ( At around 110 you don't want to keep your hand on it. And the coil will likely be 20-30 degrees hotter. That's hot.)
Sounds worse like an oil shortage somewhere or something swelled from heat binding till it cools.

Half your symptom hints of a coil getting tired. But being able to restart right away disagrees with that.
IF you have a known good condenser to swap out I might try that. Be extra careful with the points insulation they rest on too if you're near them. Look them over anyways to see it's not broken.

Along the lines of the fuel system mentions , be sure your cap is venting. Also that no line is kinked or touching a hot surface or being heated a lot.

[Torson]

Thanks for all you thoughts. I am reasonably sure it's not the fuel line. The tank looks clean as does the sediment bowl. There is a screen filter on the sediment bowl and an inline filter upstream of the carburetor. I am going to try replacing the coil. I will run it a little and check the temperature first.

[Jim Becker]

Are you sure your inline filter is one designed for a gravity fed system? One intended for a system with a fuel pump can restrict the flow and cause problems like yours.

[ScottyD'sdad]

I had one that kept stalling. It was a speck of sediment in the jet. (3/8 diameter nut on the side of the carb.Poked it a few times with a phone wire, finally blew it out with compressed air)
Ed

[Bill V in Md]

Looking back at your early posts, you were having fuel/air problems. I assume you resolved the issue back then, but maybe this is a recurrence of the same thing.

[Torson]

Thanks for the ideas. I replaced the carburetor which seemed to resolve the fuel/air problems. Since it runs fine for 20 minutes, I am thinking it's a temprature-related issue. But I will recheck the fuel line, and look at the jet.

[Eugene]

Since it runs fine for 20 minutes, I am thinking it's a temperature-related issue.

Faulty coil.

[Torson]

Easiest way to replace Coil?
a) take off hood, remove bracket holding generator, remove coil cover.
b) take off distributor, remove coil cover.
Thanks.

[SONNY]

Might want to be sure its in time before ya go taking the ignition stuff off!! LOL! --- just sayin!

[Eugene]

Easiest way to replace Coil?
a) take off hood, remove bracket holding generator, remove coil cover.
b) take off distributor, remove coil cover.
Thanks.

I believe it's a magneto. No need to remove the hood.

Might want to be sure its in time before ya go taking the ignition stuff off!! LOL! --- just sayin!

For sure. Tripple check that the number 1 cylinder is on TDC.