M Sputters Stalls When Throttled or Loaded Up

dieseldalec · Feb 11, 2011

I have a very nice 1950 M "Barn-Find" in excellent original condition. It had not been run in over 20 years when I got it from the original owners family. The rings were rusted to the cylinders when I got it. I replaced the pistons and rings, sleeves, brgs. ground the valves and seats etc. etc. All new points, cond.,etc. the carb was badly rusted internally so I did a deep cleaning using muratic acid to desolve the crust, It came out well. This tractor STARTS RIGHT UP AND PURRS LIKE A KITTEN all rpms BUT if you snap the throttle open or load the eng it sputters smokes and stalls! You can ride around the pastue on it all day as long as you don"t throttle up quick or load it. I have tried the points @ .013 & .020, checked the timing, been back into the carb several times and tried every possible adjustment and cannot figure it out ANY HELP WOULD BE GREATLY APPRECIATED to get this piece of iron history back in action.

rustyfarmall · Feb 11, 2011

(quoted from post at 09:40:23 02/11/11) I have a very nice 1950 M "Barn-Find" in excellent original condition. It had not been run in over 20 years when I got it from the original owners family. The rings were rusted to the cylinders when I got it. I replaced the pistons and rings, sleeves, brgs. ground the valves and seats etc. etc. All new points, cond.,etc. the carb was badly rusted internally so I did a deep cleaning using muratic acid to desolve the crust, It came out well. This tractor STARTS RIGHT UP AND PURRS LIKE A KITTEN all rpms BUT if you snap the throttle open or load the eng it sputters smokes and stalls! You can ride around the pastue on it all day as long as you don"t throttle up quick or load it. I have tried the points @ .013 & .020, checked the timing, been back into the carb several times and tried every possible adjustment and cannot figure it out ANY HELP WOULD BE GREATLY APPRECIATED to get this piece of iron history back in action.

Deep down in the bottom of that carburetor is a small jet made of brass. Muriatic acid dissolves brass. Muriatic acid IS NOT a very good solution for cleaning carburetors.

Yooper Farmall · Feb 11, 2011

I am no expert but whenever I hear that an engine, carb, and distributor has been rebuilt and it still runs bad I am suspicious of the governor. I"ve rebuilt all 3 and the engine purrs at low idle but surges irratically if given any throttle.
The governor is the next part to be rebuilt.

Yooper Farmall · Feb 11, 2011

If it had been sitting for 20 years, I'd take the govenor cover off and see if it is all gummed up and/or rusted or if it has freshly circulated oil running down it and moves freely.

dieseldalec · Feb 11, 2011

The carb was a boat anchor with the amount of rust. I have never used acid on a carb on any of the hundreds I have rebuilt until this one! Thats how bad it was! I did not soak it I carefully bathed and rinsed, scraped, sprayed and cleaned on it for hours-after, I had removed every thing that was removeable. Deperate means call for desperate measures! RUSTY is there a metering jet that you cannot see or access with a wire or jewelers bit? If so it could very well be plugged where I am not getting fuel through the power circuit. As far as the governor goes I think it is O.K It seems to be functioning properly.( limits top rpm, pulls back etc.)
Thanks

rustyfarmall · Feb 11, 2011

All of the jets and small passages are accessible. You just need to know where to look for them.

LaBoyteaux · Feb 11, 2011

My M (and other tractors) do the same thing and the problem is usually a gas line obstruction. It gets enough gas to run at idle or no load but as soon as it needs more fuel it sputters and stalls. The most common obstructions are crud at the gas tank outlet or crud built up on the brass screen at the float bowl inlet.
Any in line fuel filters should also be cleaned or replaced.

For rusty carburators I usually clean the iron parts in a sand blast cabinet.

John

dieseldalec · Feb 11, 2011

Rusty I have cleaned all the jets that can be seen with fine wire and jewelers bits. Again this carb was ugly! Have you ever had one you could not get cleaned?

dieseldalec · Feb 11, 2011

Yooper I just removed the gov cover inspected all components and ran with cover removed.And its clean, well lubricated, everything moves freely and no excessive play in any of the shafts, flyweights etc. its condition is representitive of the overall condition of the tractor. Good and Gently Used!

dieseldalec · Feb 11, 2011

Boytoy,
Tank was cleaned, sediment housing and bowl were tended to during overhaul. when the sediment bowl is removed fuel flows freely when valve is opened and if i discinnect the fuel line at the carb the fuel flows freely when valve is opened.
Thanks for your help1

rustyfarmall · Feb 11, 2011

(quoted from post at 10:28:15 02/11/11) Rusty I have cleaned all the jets that can be seen with fine wire and jewelers bits. Again this carb was ugly! Have you ever had one you could not get cleaned?

No, I've never had one I couldn't get clean, but I've had a couple that were quite stubborn. Almost like someone had seperated the two halves, poured tar into the bowl, put it back together and then set it up on a shelf for 20 years.

teddy52food · Feb 11, 2011

Did you check for a leak between the intake manifold & the head Or a leak between intake & exaust in the manifold?

dieseldalec · Feb 11, 2011

O.K I just pulled the carb again. It's been a while since I had done that. i tore it down and it looks very good, all brass in intact and in good condition. I double checked all passages with a lite, super thin wire, and air nozzle. all are free and clear. This carb is realativly simple as carbs go. I really think its good. the throttle shaft is just a little,little bit tight ( it wont flap around on its own when you shake the carb )It doesnt take real pressure to move it but it feels a little raspy? What is the point setting supposed to be .013 or .020 or better yet what is the proper dwell? It has a distributor not a mag.
I didnt mean to scare anyone about the acid cleaning you can be certain I used it just sparingly enough to get done what needed to be done. After looking at it I am sure all cuel and air circuits are clear and in good cond.
I really appreciate the feedback. 2 or 3 or more heads is better than 1. I know it's going to turn out to be something small and stupid!

dieseldalec · Feb 11, 2011

no but i will as soon as i put the carb back on. I will run it and spray carb cleaner @ those joints while running to look for a vacume leak. I think i had the manifolds resurfaced and installed new gaskets when I overhauled it but I dont remember right now.
Ill check in a few minutes!
Thanks

ihredo4 · Feb 11, 2011

My M did a similar thing when I had it. Took it to a friend of mine that is good with carbs and he found a blocked passage. He said he had to put a lot of air to it before it came out and he didn't even see it but heard it hit the steel wall or roof. My feeling it is the same issue with yours. Especially if it was that rusty inside.

The Dukester · Feb 11, 2011

I didn't see where you mentioned new sparkplugs and wires. If you haven't replaced these, put in new Autolite 3116 plugs and solid core wires. This may not be it, but it sounds to me like you are suffering an ignition breakdown...spark not strong enough to fire richer mixtures when you open throttle or make the engine pull hard.

Ohiohillbilly · Feb 11, 2011

I had the same problem with a 400. Plugs looked brand new. Put new ones on and it ran like a dream.

dieseldalec · Feb 11, 2011

Billy,
i put new plugs in during the overhaul but i think I will take a second look at them.

Thanks

dieseldalec · Feb 11, 2011

Dukester,
I replaced the plugs during the overhaul however I dont know what p/n I used i do know they are autolite. But one thing you mention is the wires. I did not replace those and they are autolite high tension wires as opposed to solid cores!? I will verify correct plugs and replace the wires with solid core wires.

Thanks

47farmallM · Feb 12, 2011

are you sure you got it in time right?? when i rebuilt my M i thought i had it on time, it would crank and run great but if u ever snapped it or pulled hard on it, it would just putter and die. just a thought for ya.

M Sputters Stalls When Throttled or Loaded Up

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