Farmall M Carburetor Problems

[Eboor1995]

Hi I have a 1950 farmall M that I have to have the choke 3/4 the way on for it to run correctly. I have put a whole bottle of sea foam to 6 gallons of gasoline in the tank and ran it for an hour but hasn’t helped at all. Anything else I can try before I pull the carb and put a rebuild kit in it and clean. Would rather not pull carb if I don’t have to. Thanks!

 

[Charlie M]

Has it been running OK and has just recently showed up with nothing else having been done? Are you using the sediment bowl or an in line filter? Maybe some water in the gas but if you are using ethanol gas then probably not water. After that I'd start by checking the manifold for leaks. Make sure the carb is still tight and the manifold hasn't somehow loosed up, then run your fingers around the back side and see if any holes are found. Only need to look at the intake part of the manifold. I've had manifolds develop leaks and did exactly what you are describing. They can rust through after 80 years or so. If none of that fixes the problem then we'll have to get some more minds on the problem.

 

[Mrfred54]

Have you checked the fuel flow from the tank? Should be a good steady stream for at least one minute . also there is a, or should be a screen at the top of the sediment bowl and another screen in the Fitting that the fuel line connects to. You can also try backing out the main jet a turn or so. It would be the screw at the bottom of the carb. facing the front of the tractor. Wouldn't hurt to remove the pipe plug at the bottom of the carb and let some fuel flow thru the carb to flush it good. If none of these work your probably going to have to get a carb kit to rebuild

 

[rustred]

its time to pull the carb and disassemble it and soak it in gunk for a day. dont mean u need a kit , as the gasket can be made. check float also, and make sure its set level and check the float drop. inspect the needle and seat also. it is called a carb cleaning not a rebuild. i have cleaned so many of these carbs and nver bought a kit yet. main jet out 3 turns and mixture 3/4 to 1 turn out , and idle 400 rpm.

 

[Eboor1995]

Has it been running OK and has just recently showed up with nothing else having been done? Are you using the sediment bowl or an in line filter? Maybe some water in the gas but if you are using ethanol gas then probably not water. After that I'd start by checking the manifold for leaks. Make sure the carb is still tight and the manifold hasn't somehow loosed up, then run your fingers around the back side and see if any holes are found. Only need to look at the intake part of the manifold. I've had manifolds develop leaks and did exactly what you are describing. They can rust through after 80 years or so. If none of that fixes the problem then we'll have to get some more minds on the problem.

I just bought the tractor. I bought it knowing it had some carb problems. The previous owner didn’t use it much and said it started after siting for awhile. It only has a sediment bowl. I’ll check it for leaks.

 

[Eboor1995]

its time to pull the carb and disassemble it and soak it in gunk for a day. dont mean u need a kit , as the gasket can be made. check float also, and make sure its set level and check the float drop. inspect the needle and seat also. it is called a carb cleaning not a rebuild. i have cleaned so many of these carbs and nver bought a kit yet. main jet out 3 turns and mixture 3/4 to 1 turn out , and idle 400 rpm.

How do I set the idle? How do I know what the rpm is?

 

[rustred]

How do I set the idle? How do I know what the rpm is?

its the little screw on the left where the governor connects. first thing u must have the timing set to spec, then u do your carb adjustments , and set the idle as slow as it will run basically, a nice slow idle. this is to prevent run on when you shut the tractor down after working it. its probably time for a major tune up anyhow. check the plugs .025, do a compression test, check the points .020, check the valves and set .017. set timing to tdc , you need a timing light to check the advance. may as well go through it all then you know its good. then you have a nice good easy starting and running tractor. they start on second revolution with a 6 volt battery.

 

[560Dennis]

I think that if the problem is in the carburetor ,its going need a god rebuild.
im sure you can do it yourself . Give it a try
I didn’t see anything in YT articles on how to do your M carburetor rebuild if choose to diy your rebuild .
Yt has kit here .
if you want you can watch this video to diy Carburetor . Rachel does a very good job .

 

[wwoodrow]

Hi I have a 1950 farmall M that I have to have the choke 3/4 the way on for it to run correctly. I have put a whole bottle of sea foam to 6 gallons of gasoline in the tank and ran it for an hour but hasn’t helped at all. Anything else I can try before I pull the carb and put a rebuild kit in it and clean. Would rather not pull carb if I don’t have to. Thanks!

I would remove and clean carb before I decided it needs to be rebuilt.

 

[wwoodrow]

Hi I have a 1950 farmall M that I have to have the choke 3/4 the way on for it to run correctly. I have put a whole bottle of sea foam to 6 gallons of gasoline in the tank and ran it for an hour but hasn’t helped at all. Anything else I can try before I pull the carb and put a rebuild kit in it and clean. Would rather not pull carb if I don’t have to. Thanks!

Also, probe all jet holes with wire from a wire brush or a tiny drill bit. One clog will cause your problem. Simply soaking in cleaner does not always clean these tiny passages.