F-12 fuel lines

[farmalldan4]

I am working on an F-12 kerosene model. Can I just go directly to the carburetor from the fuel pump, or do I need to go through the return apparatus that is on top of the hood?

Thanks in advance

Dan

"Grass is Green, Tractors is Red"

 

[Athol Carr]

Only a small amount of the fuel that goes through the pump gets to the carburetor, the majority goes back to the tank on the gasoline versions which cannot be done with the kerosene versions (which tank?) so the line must go to the small header tank in the hood, some will go to the carburetor and most back to the pump.

 

[SadFarmall]

There are two setups for kerosene operation on F-12 tractors. The very early ones had a triangular starting tank beneath the hood sheet. This set up is the same as for F14 kerosene tractors, other than the shape of the starting tank.
In that set up the fuel pump provides fuel from the main tank only. There is no vent through the hood, but there is a T to feed excess fuel back into the main tank.

The second set up with the starting tank inside the main tank uses the fuel pump for both the starting and main tanks. The piece sticking up through the hood is a vent, with a vented cap in it. Excess fuel flows back down the large line to a T and some is picked up by the pump. Excess can flow back to whichever tank is open if necessary.

If you use a T straight into the main tank, it will return excess fuel to the main tank regardless of whether it comes from the starting tank or the main tank.

If you simply run straight to the carburetor, you may have flooding problems if the needle and seat are not in excellent condition.

The AC fuel pump manual says, "Continued fuel pump operation fills carburetor bowl, raised float closes fuel entrance at carburetor. Pressure built up in line and pump fuel chamber forces diaphragm to take shorter strokes - stops its motion - until more fuel is needed. Normal diaphragm stroke is approximately 1/64 inch."

As IHC went to the trouble of fitting fuel return systems on F-12 and F-14 tractors, it is probably best to use them. I got new pipes for mine from Rice Equipment.
SadFarmall

 

[James Williams]

no can not go directly tp the carb,to much gas,the motor will flood

 

[farmalldan4]

Not trying to argue with anybody, but pictures that I see of the gasoline model show the fuel line running from the fuel tank to the fuel pump and straight to the carb. It appears that they have the same fuel
pump and carb. Just trying to understand the difference.


Dan

"Grass is Green, Tractors is Red"

 

[John M]

Cant be, or as mentioned the carb will flood. Also, the tee that was mentioned isnt just any ordinary tee. Theres a smaller hole in the side that screws into the tank. A regular tee will allow too much fuel to go back to the tank and not fill the carb.

 

[farmalldan4]

 

[farmalldan4]

Several years ago, I was told this about what the “tower” on the distillate models was used for.
If you were running on distillate and for whatever reason the engine quit, you couldn’t restart the engine with distillate in the system. You then had to drain the distillate out of the carburetor and close the valve on the main tank. You would then open the valve on the small tank to allow gasoline into the system. Then you had to remove the plug in the top of the tower and pour gasoline in there which would fill the carburetor bowl with gasoline. You were then able to restart the engine on gasoline and go through the procedure for switching back to distillate.

 

[John M]

I dont see how it stays running without flooding, but Id be danged if I would have ran the fuel line through the manifold like that.

 

[John M]

This is what a straight gas should have.

 

[SadFarmall]

Here is a thought about the return T and why it might work on a straight petrol / gasoline tractor without it.

The fuel pump on the F-12 is an AC 152 1394, which produces 2.5 to 4 lbs static pressure when tested on the engine, according to A.C.

Consider a motor car from the same period as the F-12 tractor. The car has an A.C. fuel pump, with a pipe direct to the carburetor. There is no return line.

If the needle and seat in the F-12 carburetor work as well as in other carburetors of the day, the pump should stop supplying fuel, when the float rises and the needle closes entry to the carburetor.

The picture below shows why it should be possible to run direct to a carburetor. The pump draws fuel from the tank by pulling down on the diaphragm. The spring under the rocker arm forces the diaphragm back up and pushes fuel through the pump outlet. When the carburetor needle shuts off fuel supply, the diaphragm in the pump is held down by fuel. The rocker arm does not move again until the diaphragm lifts. The diagram is not from an F-12, but the principle is the same I think.

All that said, IHC put a fair bit of plumbing on these tractors and presumably they felt it was there for a reason.
SadFarmall

 

[Athol Carr]

On the straight gasoline tractors the return to the tank has a slight upstand to provide a small head on the line to the carburetor. If you listen whilst cranking you can hear the fuel running from the upstand and dropping into the fule in the tank.

 

[SadFarmall]

Looking through the F-12 Parts Catalog and found that nine tractors were built with a fuel line direct from the fuel pump to the carburetor. These were FS600 to FS608, which were the first F-12 tractors to use the IHC engine. After that, all F-12 tractors with IHC engines had a fuel reflow system.
The pipe from the pump to the carburetor was 25837 DX.
SadFarmall

 

[Knees.bones]

There are two setups for kerosene operation on F-12 tractors. The very early ones had a triangular starting tank beneath the hood sheet. This set up is the same as for F14 kerosene tractors, other than the shape of the starting tank.
In that set up the fuel pump provides fuel from the main tank only. There is no vent through the hood, but there is a T to feed excess fuel back into the main tank.

The second set up with the starting tank inside the main tank uses the fuel pump for both the starting and main tanks. The piece sticking up through the hood is a vent, with a vented cap in it. Excess fuel flows back down the large line to a T and some is picked up by the pump. Excess can flow back to whichever tank is open if necessary.

If you use a T straight into the main tank, it will return excess fuel to the main tank regardless of whether it comes from the starting tank or the main tank.

If you simply run straight to the carburetor, you may have flooding problems if the needle and seat are not in excellent condition.

The AC fuel pump manual says, "Continued fuel pump operation fills carburetor bowl, raised float closes fuel entrance at carburetor. Pressure built up in line and pump fuel chamber forces diaphragm to take shorter strokes - stops its motion - until more fuel is needed. Normal diaphragm stroke is approximately 1/64 inch."

As IHC went to the trouble of fitting fuel return systems on F-12 and F-14 tractors, it is probably best to use them. I got new pipes for mine from Rice Equipment.
SadFarmall

 

[Knees.bones]

Hi. I'm restoring my grandfathers F12 FS3426 here in NZ. It was somewhat in bits when I got it, and I'm about to get new fuel lines sorted out. It has this triangle shaped starting gas tank mounted under the hood, and I've been unable to find any pictures online anywhere of this style of tank. Some have told me on Facebook that it's not a standard F12 tank. But I recently came across your comments here, and note you refer to the very early F12s having a triangle tank under the hood. Is this what I'm dealing with here? With regards to the plumbing, am I correct in setting up the fuel lines as you have explained in your comments for the early F1 kerosene tractors? Thanks, Stu

There are two setups for kerosene operation on F-12 tractors. The very early ones had a triangular starting tank beneath the hood sheet. This set up is the same as for F14 kerosene tractors, other than the shape of the starting tank.
In that set up the fuel pump provides fuel from the main tank only. There is no vent through the hood, but there is a T to feed excess fuel back into the main tank.

The second set up with the starting tank inside the main tank uses the fuel pump for both the starting and main tanks. The piece sticking up through the hood is a vent, with a vented cap in it. Excess fuel flows back down the large line to a T and some is picked up by the pump. Excess can flow back to whichever tank is open if necessary.

If you use a T straight into the main tank, it will return excess fuel to the main tank regardless of whether it comes from the starting tank or the main tank.

If you simply run straight to the carburetor, you may have flooding problems if the needle and seat are not in excellent condition.

The AC fuel pump manual says, "Continued fuel pump operation fills carburetor bowl, raised float closes fuel entrance at carburetor. Pressure built up in line and pump fuel chamber forces diaphragm to take shorter strokes - stops its motion - until more fuel is needed. Normal diaphragm stroke is approximately 1/64 inch."

As IHC went to the trouble of fitting fuel return systems on F-12 and F-14 tractors, it is probably best to use them. I got new pipes for mine from Rice Equipment.
SadFarmall

 

[SadFarmall]

Yes, the triangular tank is factory. I had to make new pipes for mine. I have samples if any of yours are missing and you need dimensions.
SadFarmall