1964 4000 Gas Sputters and Dies

ChrisT

Member
My 4000 with a 172 gasser will run for about 5 minutes at a time and then sputters and dies. If I mess with the throttle, I can keep it running but it runs rough and won't come back to high idle before it dies. I replaced the carb, and rerouted the fuel line. When I bought the tractor it had the fuel line running between the head and exhaust manifold. I thought it might be vapor locking so i rerouted it. I hooked up a timing light to all the plug wires, it's not losing spark. About 30 seconds after it dies, you can hear gurgling through the intake. If I remove the fuel cap, air seems to be purging back into the tank. I'm out of ideas. Any one have some?
 
Leave the gas cap loose and see if it will run.
Fuel line was in its original, intended location.
 
Tried leaving the gas cap loose. I rebuilt the engine 20 hrs ago, and it has ran fantastic up to this point.
 

Sounds like you've got a fuel restriction somewhere. Could be in bottom of tank or anywhere else between there and the intake manifold.

After it's run for 5 minutes and dies, how long does it have to sit before it'll run another 5 minutes?
 
Less than a minute. There is nothing in the tank restricting it, new fuel line, and last night I pulled the carb and sediment bowl to ensure they were clean.
 
I think I may have figured it out. After doing some research, i believe the fuel manure off valve is too small. The one on the tank has the brass knob, and everything I can find shows that is the one for the diesel model that takes a smaller fuel line. I'm going to order the correct one and see what happens.
 
One way to check is to remove the bowl plug and check the flow rate. A piece of debris could also restrict flow past the manure valve. Sometimes they dislodge and move to a smaller point like a clot in an artery.
 
I don't know, but some carburetor systems have a secondary screen system where the fuel line enters the carburetor. Does the ford 4000 gasser have one of these?
 
"There's a screen that sticks up in the tank...but no other screen past that."

There should be a sediment bowl mounted to your carb.
In the top of that sediment bowl there is/was a screen.

This one is mounted backwards, fuel line out, for testing.

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I replaced the sediment bowl when I replaced the carb. Just removed it to double check and there is no screen in it. It also has no restrictions.
 
Sometimes people take them out because its easier to get the
sediment bowl to seal without them. Once you find the culprit for
the current situation I would put one back in there above the seal.
 
The quickest flow check is to just remove that bowl plug and see how long it takes to fill a cup or bottle. That is the end of the line. If fuel does not flow well here you have a problem upstream of the needle and seat. If it flows well then your float may be set a wee bit too low or may be jamming.

Next test. If the fuel is flowing well run the tractor until it starts to complain. Gently tap the side of the carburetor bowl with a 1x1x8 inch piece of hardwood. If the engine picks up you probably have a jammed float.

Probability says that a low set float or jammed float is not the problem. The reason is that a float usually allows a higher fuel level in the carburetor as it ages. The only instance I can think of that might change that is the float getting jammed during bowl reattachment. Since it has been running well for 20 hours all of this is unlikely unless you recently removed the bowl and the float got off center or jammed. You can test this by removing the drained carburetor and just inverting it. You should hear and feel the float flopping.

Unless you just replaced that fuel valve and the problem simultaneously began the valve seems unlikely, but that gurgling sound is curious.

If this does not work use a three foot 4x4. Then get a new carburetor. That was a joke.
 
Just a thought. The following might be done only after you have thoroughly gone through the fuel system and have totally eliminated it as the problem.

Check the radiator coolant level and watch for the sheen of oil or fine bubbles on the coolant surface.

Also check the level and condition of the oil.

Lastly, check the torque on the manifold nuts. Slight possibility of a warped manifold or loosened nuts.

All of this is unlikely, but still check it.
 

I replaced the shut off valve, and it runs great now. I disassembled the old shut off valve and it was not opening all the way. Thanks everyone!
 

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