Farmall H carburetor trouble

The only way i can get tractor to start is to hold the palm of my hand over the carb air inlet. I know i am going to need to replace the carb, but i just want to know what is causing this. I put a carb from my brothers tractor on and it runs perfect. I have cleaned it several times. Once it starts, it only runs for a few seconds. And should i get a good carb kit, or just replace the whole thing. Thanks

Something is plugged. But first open the load screw. it maybe screwed in too far.Or the float is set too high.Or the needle it
stuck. Open the bottom carb drain,let it run for 5 min or so to confirm good gas flow.It is simply starveing for fuel.

"Cleaned" it how? Did you have the nozzle out?

.Thanks for the reply. ive done all that and i even soaked it in solvent for 3 months while i used my brothers carb. i agree something has to be plugged but what it is must require a lot stronger solvent. i ran trhough every hole i can see. I have turned the adjustment screw all the way in and out to the point it is loose with gas leaking out and its always the same result. i soaked it in parts cleaning solvent. and even squirted carb cleaner through everything. thats why im thinking of getting a completely different carb. dont want to get a carb kit and have the same problem. I have good fuel flow through. it just doesnt seem to want to suck it up into the intake. and it is very strong suction. It just has me puzzled. it sat 2 months without being run and when i went to start it, thats when i started having the trouble.

Did it do this before you worked on the carburetor?

The venturi fell out of mine when I cleaned it, and showed the same symptoms, put it back in and all is fine.

no. this tractor has ran like a top as long as i have had it. "over 15 years" and never touched anything on it. so when it did this i tore carb completely apart, cleaned everything, put it back together and no change. put different carb on it and that carb ran fine. so i tore mine apart again and soaked it in solvent for over 3 months. didnt change anything. Like i said, i am going to get a different carb for it, but it just puzzles me what could be causing it.

Delta is correct.....check for load needle turned in too far. That controls the amount of fuel going into the air stream. Nephew couldn't get one running after cleaning.....had load needle turned in almost closed.

Is the load needle the one on the bottom of bowl at an angle, If so. i have tried adjusting that one from 1 turn out. all the way to the point that it is so loose fuel leaks out of it.

will it run with the choke partly closed

(quoted from post at 16:12:46 11/08/15) will it run with the choke partly closed

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o. will not run unless you hold your palm over air inlet. once it starts to chug remove my hand and will run only for a few seconds. i tried both the idle mixture screw and main adj. needle and same result.

Sounds to me like you have something wrong with the venturi. Are you sure you put it back in right when you cleaned it? Can you keep it running by just letting a little air in with your hand? If you run a quart into a can through the carburetor drain and it is still running good then it is not the needle valve. But run a full quart to make sure something does not plug up and slow the flow down, don't just open and drain a little fuel from the bowl, that tells you nothing. They are really simple carburetors and there is an obstruction or the venturi is in upside down. Take the main jet out and verify you can see light through the holes. I would wager the venturi is in upside down.

If i try and move my palm a little i can get it to run for a while by controlling how much air i let thru. What direction should the venturi be sitting. It is round on one side and square on the outside of the other end. should the round end be facing upward or down.

I didn't think the venturi COULD be putin upside-down. But that would sure mess it up. Here's my carb procedure, you may already have seen this;
Make sure the float isn?t sticking or touching the insides of the float chamber. Some previous advice was to use a Dremel tool and smooth the insides of the float chamber so the float doesn?t rub or touch. Pretty important.
Set the float so the top of it rests 1 27/32" above the flat surface of the float chamber.
[Note a new float might already be set correctly.]

INITIAL settings are as follows to get the engine started;
Main fuel adjusting screw; big screw facing down at an angle, towards the rear, at the bottom of the carb; 2 1/2 to 3 turns open. This main screw turns clock-wise for leaner mixture. [This screw adjusts fuel.]
Idle-air-mixture screw; smaller screw facing forwards, on upper left-hand side of carb; 1 to 1 1/2 turns open. This idle screw turns counter-clockwise for leaner. [This screw adjusts air.]
Idle speed screw; faces outboard, at the top of the carb; set for 450 rpm, and make sure the governor correctly engages in the slot. [This screw adjusts RPM?s.]

FINAL settings are as follows;
Get the engine warmed up, and idling.
Turn OUT the small idle-air-mixture screw until rough running, then turn in until engine idles smooth. (Mine is set at 1 turn open.)
Rev it up, wide open, warmed up, then turn the big main fuel adjusting screw IN until rough, then out til smooth, then 1/4 turn to 1/2 turn further out. (Mine is set at 1 turn open. Other advice has been to set it at 2 1/2 turns open for pulling implements.)

Engine should rev up smoothly and evenly.
Too Lean = stumble, sputter, damaged melted plugs.
Correct = tan plugs.
Too Rich = back smoke, black sooty plugs.

I have rebuilt a bunch of H carburetors. The venturi CANNOT be installed upside down. It physically will NOT fit that way.

So far, no one has mentioned the fuel inlet fitting. This fitting has a very fine mesh screen attached to it. That screen IS the fuel filter. Remove the fitting and clean the screen with aerosol carb cleaner and compressed air. Also, did you make sure the float height is correct? Is the float free to move up and down, or is it twisted slightly so that it makes contact with the side of the fuel bowl?

If the float height is too low, it won't allow sufficient fuel to enter the bowl, and the engine will not run.

Simply soaking it in carb cleaner for 3 months accomplishes nothing. The carb must be totally disassembled first and even then you need to know WHERE to look for the dirt and crud.

More often than not a rebuild kit will not be needed. All you will need is a gasket set.

(quoted from post at 07:12:11 11/09/15)
I have rebuilt a bunch of H carburetors. The venturi CANNOT be installed upside down. It physically will NOT fit that way.

So far, no one has mentioned the fuel inlet fitting. This fitting has a very fine mesh screen attached to it. That screen IS the fuel filter. Remove the fitting and clean the screen with aerosol carb cleaner and compressed air. Also, did you make sure the float height is correct? Is the float free to move up and down, or is it twisted slightly so that it makes contact with the side of the fuel bowl?

If the float height is too low, it won't allow sufficient fuel to enter the bowl, and the engine will not run.

Simply soaking it in carb cleaner for 3 months accomplishes nothing. The carb must be totally disassembled first and even then you need to know WHERE to look for the dirt and crud.

More often than not a rebuild kit will not be needed. All you will need is a gasket set.

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es. I have completely disassembled it. The fuel inlet screen is clean. I blew compressed air through everything, even though the gaskets "look" good. That's what I'm thinking must be the next step.I will get a good quality set and try that. Thanks for all the responses.

(quoted from post at 08:17:46 11/09/15)

(quoted from post at 07:12:11 11/09/15)
I have rebuilt a bunch of H carburetors. The venturi CANNOT be installed upside down. It physically will NOT fit that way.

So far, no one has mentioned the fuel inlet fitting. This fitting has a very fine mesh screen attached to it. That screen IS the fuel filter. Remove the fitting and clean the screen with aerosol carb cleaner and compressed air. Also, did you make sure the float height is correct? Is the float free to move up and down, or is it twisted slightly so that it makes contact with the side of the fuel bowl?

If the float height is too low, it won't allow sufficient fuel to enter the bowl, and the engine will not run.

Simply soaking it in carb cleaner for 3 months accomplishes nothing. The carb must be totally disassembled first and even then you need to know WHERE to look for the dirt and crud.

More often than not a rebuild kit will not be needed. All you will need is a gasket set.

Click to expand...

es. I have completely disassembled it. The fuel inlet screen is clean. I blew compressed air through everything, even though the gaskets "look" good. That's what I'm thinking must be the next step.I will get a good quality set and try that. Thanks for all the responses.

Click to expand...

The gaskets will not cause the problem you are describing. There is still some crud in there somewhere. Did you poke a wire down through the idle metering jet?

I had a hole in my manifold that let exhaust gas leak back to the inlet. The excess air caused it to run only when choked.

OP stated he changed carburetors and it ran fine.