F 14 fuel system

F 14 starting problem. pre messages said to check for float hieght, that should be how much. This 14 starts hard cold, good when warm,have checked timing, new coil, poins & condensor,impulse snaps loud and clear. And as usual only pull few feet to start. Pulled carb this AM and it was bone try.
previuos note on changing manifold from hot to cold. Where is this located??
Also it has a tee fitting at top front of fuel tank, pressure line fuel pump to it and aline to the carb. what is the purpuse of this fitting??

If the bowl on the carb is "bone dry" that tells me the float is sticking. When the float and valve are working properly you should have about 3/4" of fuel in the bowl when you remove the top. The fitting at the top of the tank has a line from the fuel pump and one to the carb. If you were to remove the fitting you would find a small tube about 1" long and about 1/8" in diameter thats inside of the tank. The purpose of this fitting is to return any fuel that is not used by the carb back to the tank as well as provide a positive pressure to the carb. The fuel pump puts out more fuel than the carb uses hence the small tube. Since you have the carb off, I would check the inlet fuel screen. Thats the fitting on the carb that the fuel line screws into. You might also check the float for any fuel sloshing around in it. That is a no-no. With a possible leak in the float, it won't open up the needle to admit any fuel. Just some things to check.

That is a great explanation. However, I have seen some F-14's that didn't have this arrangement. Could you explain further/

You are probably thinking of the fuel line vent made out of cast that sticks up through the hood right in front of the fuel tank. It has a plug on top of it with a bleeder hole drilled into it. It works on the same principle. There is a pressure line from the fuel pump to the vent at a tee at the bottom of the vent. The other side of this tee goes to the carb. There is also a larger line, about 3/8" that comes out the bottom of the vent and goes to a tee in the line from the tank to the fuel pump. This is a return line for the excess fuel the pump puts out and the carb can't use. The internal construction ensures there is always positive pressure on the line to the carb and the excess overflows into the return line. As said, the same principle, just a different way of doing it. It is a matter of gravity. If the vent housing is working correctly, the line to the carb stays full, and any excess is returned to the intake of the fuel pump. That's why the vent in one case and the tee in the top of the tank being the other case, are higher than the inlet to the carb. Hope this clears things up.

Actually, I think you'll find that if the float is waterlogged (full of gas) it will sink and OPEN the fuel inlet, causing flooding. I had that problem with mine.

Unless you're killing the tractor by turning off the fuel and letting it run until it stalls, there should be gas in the carb even after it's been sitting for a few days. If it's dry, you have a leak somewhere draining the fuel out of the carb bowl.

If the carb is dry after cranking, you have a fuel inlet problem, either the float/needle assembly is sticking, the inlet filter is partially plugged (as it will start/run when pulled, it can't be completely plugged) or the fuel pump is too weak to push fuel past the filter at hand-cranking speed. When you pull it, the engine is turning over faster, running the fuel pump faster.

I stand corrected on the float. I guess I was looking at it upside down. Everything else I agree with.

The float is ok, I'm looking for a float setting. From what I can see it would have to an external leak to drain the carb.???
the fuel has to up from the main jet? (I think). Once upon atime I had a book with workings of a H or M carbs.
Did they have such a thing for the F 12&14 carbs ??

Not hard to do, for sure. Wish I had a nickel for every time I've done that.

Durn thing was driving me buggy, just kept getting harder and harder to start until it wouldn't start under ANY inducement.

Old feller that spends his summers up here usetabe the IH field rep for New England. I live right across the street from the Post Office and when he came to get his mail one day, he saw me fussing with it (and probably heard me mumbling incantations...) and walked over and put me right on to the problem, plus offered to hit up his contacts for a good float.

Ol' gal has run like a top ever since.

You are probably thinking of the fuel line vent that sticks up through the hood right in front of the gas tank. This has a plug on top that has a breather hole drilled in it that allows atmospheric pressure in. On the bottom there is a tee, the bottom connecting to the fuel pump outlet and the side going to the carb. The other fitting is larger and is a return to a tee in the inlet line to the fuel pump. The internal construction of the vent ensures a positive pressure on the line going to the carb. Since the fuel pump puts out more than the carb can use, the overflow enters the return line to the tee in the inlet line to the fuel pump. It's the same principle as the restrictor tee, just a different way of doing it. As you can see both the tank tee and the fuel line vent are both higher than the inlet to the carb. It's a matter of gravity.

My reprint manual says the fuel level should be 23 to 25 32nds below the bottom of the upper body.

JLE, my comments on setting the manifold may or may not apply to you. If you have a dual fuel manifold (ie. distillate and GAS), you will have a larger square area in the middle of the manifold with a lever sticking out of it. That is a butterfly valve to redirect the hot exhaust past the intake portion of the manifold. This in turn heats up the intake and the carb. If you are running distillate, absolutely necessary to vaporize it. Since I was running gas, no need for the extra heat, and it appeared to me to be boiling off the gas in the bowl after the tractor was shut down, and left till the next day. I can tell you that when I set the butterfly valve to the "cold" or "gas" setting, my problem went away.

If you don't have a dual fuel manifold, this is NOT your problem.

If you do, you want to check that the butterfly valve is shut, so that the exhaust does NOT flow past the intake portion of the manifold. May or may not be your issue, but it certainly helped me out.

The carburettor sits on top of the manifold with an insulating washer. If the engine is hot some heat will reach the carburettor after stopping the engine, the insulating washer is not perfect, and will vaporize the fuel. Even the gasoline engines had a heat control flap in the manifold that can be adjusted to vary the amount of heating the fuel-air mixture gets before reaching the cylinders. There were two fuel arrangments, the ones on the F-12 and some early F-14s where both fuels fed the fuel pump, the fuel from the pump went to a small vertical chamber sticking up through the hood just in front of the tank, this had a vent to air at the top, a pipe to the craburettor and a return back to the pump inlet line (this provided some head to the carburettor). The other version used on the later F-14 and all the W-12, O-12 etc. tractors had only the main fuel going to the pump and in this case the line from the pump went to T junction in front of the top of the tank, the wee upstand inside the tank gave about 1/2" head to the T, the other side of the T went to the carburettor. If it was a kerosene or distillate engine the gasoline starting tank was, in this case, set in the hood (a 7/8 gallon cylinder on its side) with two valves giving feed from the pump for normal running or feed by gravity from the gasoline starting tank for starting.
If you do not have a starting tank it takes a bit of cranking to get the carburettor full if it has emptied by evaporation.
There is also a fuel filter built into the inlet to the carburettor and if this is blocked then you could crank for ever!