Farmall M 1941 - Stalling

[Nikolaijg]

This is my first tractor project, and this tractor is three times my age but I've always had a love for old machinery and trying to fix them up because they just last forever compared to modern technology with that old American steel and relatively simple designs. I've been combing through manuals and videos trying to teach myself and I've made some good headway on the old beast. It already had a 12v swap and a paulson loader, but wasn't really running well when I got it.

I did my best to tune it up, new plugs/wires, rebuilt the carb, oil change and just in general cleaned things up and at this point she fires right up without choke. The problem is after about 5 minutes of running she will start to sputter out and if I pull the coke out completely and give it throttle I can keep it going for another 5 minutes roughly. After it dies if I let it sit for a bit I can start it back up without choke and continue the cycle. My assumption so far has been some sort of fuel problem, but the tank seems clean, I took the sediment bowl off and cleaned it out, made sure it drips and flows fast. Pulled the carb multiple times and just double checked things but it always has fuel in it with no leaking. I'm just at a loss and pretty green on the subject, curious if anyone else has had a similar issue.

 

[TractorDad3]

Make a good plan of how to troubleshoot. Try not to succumb to
buying parts to fix a problem!



Make sure fuel flows out of the sediment bowl and out the carb
drain at a rate of a pint every 2-3 minutes



Keep your body safe during all of your inspectionsdisconnect
battery and Check and clean all your electrical points of
contact. New coils are garbage these days, so be diligent when
using a voltmeter to check that you have adequate power on the
distributor side of the coil. A good idea to check that when she
sputters down. Spit on the coil and if it steams off it likely has
gone bad.



Report back on what you find so others can offer further
direction.

 

[Charlie M]

Next time it dies immediately pull the plug in the carb and let the gas run enough to get a cup or two. It should flow with a pretty good stream the whole time. If the stream doesn't last you have something
going on in the fuel line, possible at the outlet of the tank. You need to try one thing at a time to start eliminating potential problems so you don't buy parts you don't need or get frustrated because
nothing your are doing is working. Could be an electrical problem but I would deal with gas flow first. You mentioned the sediment bowl - did it have a screen in it? Also there should be a screen in the
fitting to the carb. I had something looking like mold in the one on my 300U once plugging it up. My F14 had a fuel line almost rusted closed when I got it. Lots of possibilities in the fuel system these days.

 

[BarnyardEngineering]

You used the word "drip." The fuel should not "drip" at all, ever. A drip is not enough fuel flow to keep the tractor running.

 

[Nikolaijg]

When I reinstalled the sediment bowl, at empty it filled in maybe 15-20 seconds would be my estimation. The carb has a new screen on it, and since I've been wracking my brain trying to figure this out I've opened and sprayed it back out probably three times. There was a bad float in it for a while that would keep jiggling the pin loose and then half fall off but I got a new tight one in there but unfortunately didn't fix the issue.

Looking at your suggestions so far I disconnected the fuel line to the carb and with the petcock open I'd say it runs at a fast trickle, almost a steady stream but slow enough to notice some individual drops.

I reconnected that and fired her up again, let it sputter out after needing to pull the choke and then ran over to open up the carb bowl and fuel came out steady for a couple seconds before going empty.

Edit: based on everyone's comments that sounds like fuel must not be getting to the carb fast enough, once I get back from work tomorrow I'll try cleaning everything out between the tank and the carb and see if I can get the fuel flow increased.

This post was edited by Nikolaijg on 08/22/2022 at 01:09 pm.

 

[Charlie M]

Now you've got places to start looking. I would check the screen at the carb, make sure the fuel line is clean and see if you can see the outlet of the tank for something in the opening. My H once had a jell
like substance plugging the outlet. Old tanks can have stuff moving around that shouldn't be there.

 

[Paul from MI]

make sure the vents in the fuel cap are open. Could be air locked.

 

[caterpillar guy]

You found your problem the lack of fuel drip drip drip. Now check the flow at the tankif a good full stream filling a pint jar quickly then move to the next joint at the carb where the line screws in if no fuel there you have a plugged line if no fuel flow from tank then you have a plugged sediment bowl or tank fitting. I would guess if you take the top of the sediment bowl out of the tank and clean it out it will flow fine.

 

[caterpillar guy]

If after you clean out the top of the sediment bowl when you put the glass bowl back on if it will fill with it tight you have an air leak in the bowl gasket or a leak further down the line.

 

[Rich'sToys]

If it does turn out to be not fuel related, check the coil. A bad coil will run fine when cold, but will act up as it gets warmed up.

 

[used red MN]

Hello NIK welcome to YT! So for one to clarify what
you are saying about cleaning the screen in the inlet
fitting of the carb. Are you unscrewing the fitting out of
the carb and cleaning or spraying it off that way. I do
not not your tendencies, I could take what you say as
..I got frustrated and took the line loose and sprayed it
out the best I could with the fitting and screen still in
the carb. That will not clean it good enough. It sounds
like your problem is somewhere upstream of the
carburetor. You say the tank looks clean, what you may
not be noticing is the baffle in the back half of the
tank. You have no idea what kind of crud may be back
behind there slowly making its way into your fuel
stream. Get a good flashlight and look down in the gas
cap at the spot the sediment bowl screws in the tank.
Is there anything floating around there that could plug
the fuel hole into the sediment bowl? Also the top of
the sediment bowl should have a fine screen. If you do
not have one you should acquire one. An additional
helpful item is these little strainer screens YT sells to
go in the sediment bowl in the tank to keep crud from
plugging the outlet of the tank, see 1st link. Just for
grins I added in the 2nd link the manufacturer online
part diagrams. It will open to the sediment bowl
diagram, number 7 is the screen I was talking about.
Find yourself and aftermarket one, CNHI thinks they
are made of gold. From that page you can view all the
parts sections for your tractor. On a PC you can
navigate back to the main sections, also on a phone if
you hold it sideways. I will tell you for sure that their
site doe not play well with an iPhone. If all else fails
you can just search Farmall M again. Also just be aware
a lot of part numbers and descriptions have been
removed. Good luck!
Sediment bowl strainer

CNHI Farmall M parts diagrams

 

[redforlife]

You said you took the sediment bowl off and
cleaned it. Did you just remove the glass
bowl, or did you unscrew the whole sediment
bowl assembly and removed the entire thing
from the bottom of the tank???
Because this sure sounds to me like
cloggage in the pipe that goes upward into
the tank where the sediment bowl assembly
screws into the bottom of the tank.
Cloggage here will often reduce flow, and
not completely shut it off.

Wouldn't have to be it. But it would be my
first guess if it's fuel related.

 

[Nikolaijg]

Hey thanks for the advice, I'll definitely grab a screen for it while I'm in there. The carb inlet screen is brand new brass, I got a whole rebuild kit that replaced every part on it, bushings and all. That is not to say that there haven't been frustrated moments along the way haha. I went to a parts store and they gave me the wrong oil filter like three different times and the new rings never fit.

 

[Nikolaijg]

Just an update, I got some gunk out of the tank and petcock for the sediment bowl and now it's flowing like a faucet. This definitely solved the stalling problem, and it sounds and runs better to boot with no need for any choke anymore.

Now that the fuel pressure is up of course the carb is now leaking out of the gasket so I got to go back and fix this, even though the float and needle are all new, but at least she's running now!

Edit: I've done some reading around and it sounds like a lot of people have had issues with the rubber tipped float needles, anyone experienced that and if so know where to get an all brass one?

This post was edited by Nikolaijg on 08/24/2022 at 08:55 pm.