Super M wont keep running

I have a Farmall Super M. It's always ran well. We've been having severe cold weather, so I originally suspected some ice in the gas. I've put in 4 containers of HEET in the last few weeks. The problem just wont go away. Even when we had on a few warmer days (above freezing).

Here's what it's doing. It starts fine, choke is fully closed. As soon as it starts I open the choke slightly and it runs great. But after a minute or so it begins to spit and sputter. loses power, and on occasion shoots a flame out of the muffler. Going up a hill or any load, such as pushing snow with the loader makes it worse. The longer it runs the worse it gets, and just to keep it running I have to fully close the choke, and keep it closed. It will stay running that way, but if I try to push any amount of snow, or a round bale, it struggles to stay running. At this point, if I open the choke, it shuts right off.

If I shut it off, and let it rest for a few minutes, it will once again run well for a minute and then repeat this all over again. It most definitely seems to act like it's running out of gas, more than an electrical issue, but I wont rule out anything. I am not low on gas. I have not tried to adjust the carburetor, because it does run well when I start it, and was running well prior to this issue (and I dont recall what screws to adjust either). The bowl is filled with gas even after it begins to run poorly.

One thing I am also noticing is that the top part of the carburetor and lower end of intake manifold become encased with frost on the outside after it runs for awhile. I was told this is normal, but I never noticed it in the past, but at the same time, I dont normally look at the carb when the tractor is running well.

What could be the cause of this? I should mention that on occasion it will run perfectly fine for 10 or more minutes, but the next time I use it, the problem returns. I'm puzzled, and it's too cold outside to start ripping everything apart not knowing the exact cause, other than it's most likely fuel related.

Any suggestions, or tips to test things?
Thanks

Check your air cleaner. Take the bottom bowl off to see if there is dirt/ice, etc in it. Another quick test is to take the air cleaner hose off and see if it has any effect on this behavior.

also, check the fuel screen on the sediment bowl and if there is one on the carb inlet. make sure you have good fuel flow the entire way along the fuel delivery path.

icing on the carb exterior is normal, although it would be interesting to use a blow dryer while you are having the symptoms to heat up the throat area of the carb while running.

Last question, do you let it come up to temp before you start working it? at first, this sounds similar to a condenser problem, however, that would not explain why it will run with the choke on......so check out the fuel delivery first.

Sediment bowl screen, carb screen, standpipe partially plugged, point adjustment, coil or coil wire.

Allan

You have answered your own question. It's not getting enough fuel. Either a restriction/junk in the fuel line, junk in the carb, or improper high idle screw adjustment.

Gordo

Pull the fuel line at the carb and turn on your gas. Stream should be pencil thin and constant. Shawn

Check the fuel system as the fella above said. You said you had trouble with carb. iceing up.It is posablethe throttle plate is freezing up.had a ih b that would freeze up. took a 6" stove sliped over muffler and made a pipe from stove pipe to top of air cleaner stack. carb. never freezes up. i take it off in warm weather.we have used for 30 years with no problems.

hang a 'curtain' along the side to direct warm air to the carb.I once had a '41 M that did the same thing.The curtain 'cured'it.

Yes check the fuel flow to carb, should be a full stream. If not, make your way up stream to the tank and don't forget to make sure the fill cap is venting properly. If you have a full stream, the fuel isn't getting past the needle. I recently fixed a carb that the fuel level was too low and would only let in a little fuel. Another time I found a bad float. But before you open up the carb, remove the fuel line and make sure that nothing is blocking the fuel before it gets to the carb.

One more thing, check your coil. That is also typical of a weak coil.

Good luck!

(quoted from post at 11:44:50 01/16/11) Pull the fuel line at the carb and turn on your gas. Stream should be pencil thin and constant. Shawn

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Also check the carb inlet screen while the line is off.