Farmall A only runs with choke half on

Mr. Farmall · Mar 27, 2017

What I thought was a sticking needle valve has turned out to be something else. Engine will only run with choke half on, and it is still somewhat rough. It can idle without the choke but stalls right at half throttle with no choke. Installed a new needle valve, checked float height, and still no improvement.

I do not think it is a vacuum leak, as vac leaks usually hurt idle much more than part throttle or WOT. In my case, the idle is ok but throttle opening is the problem. I did still spray carb cleaner on the gaskets and did not detect any change in rpm. Hopefully the needle valve did not go bad right away but that is unlikely.

SW EM · Mar 27, 2017

There must be some sort of fuel restriction occurring. Open the drain on the carb to check for a steady stream of fuel for 2-3 minutes. If that checks out ok, then manually clean all the passages within the carb using a small wire.

These little issues can be irritating sometimes, but I guess it means that the tractor just wants to spend more time with you

khouse6 · Mar 28, 2017

on the c, i usually have to clean the fuel shut off valve, on the bottom of the gas tank.

Oregon Tractor Jack · Mar 28, 2017

You might have to repeat the carb cleaning several times. I had an H that took like three times before I got it clean. I use a tip cleaner from my torch set. Lots of little stiff cleaners of all different sizes. Lots of compressed air and carb cleaner. Treat and of the brass jets with TLC if you are using a tip cleaner set.

OTJ

Fire50 · Mar 28, 2017

The jet is cogged. Jet is not removable if you a M/S tsx carb. Jet is located in bottom of carb. on float side take a fine piece and clean jet and blow out good had same problem on mine years ago hope this helps

denglish · Mar 28, 2017

I had similar problem on my M. Would only run with half-choke and had low power and missing under load. Turned out to be low fuel flow due to crud clogging the passage between fuel tank and sediment bowl.

Mr. Farmall · Mar 29, 2017

The carb on my A is a Zenith. I think I may have found the problem. The fuel strainer was clogged just under the shutoff valve in the little discharge port into the glass bowl. Also found the bowl gasket is bad and have to wait for replacements to arrive.

denglish · Mar 29, 2017

While you are waiting for parts, you might consider taking the gas tank off and rinsing it out if you think there is more litter inside. You could just slosh a pint or two of gas around and then pour it out the top and see what comes out. Rinse and repeat until clean.

Farmall A only runs with choke half on

Mr. Farmall

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SW EM

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khouse6

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Oregon Tractor Jack

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Fire50

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denglish

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Mr. Farmall

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denglish

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