Carburetor Fitting

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Speedracer
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Carburetor Fitting

Post by Speedracer » Sun Mar 17, 2019 12:03 pm

I've noticed in other posts that there is a Tee fitting on the carburetor; my M274A5 only has a 90-degree fitting going into it, not a Tee. Does the other line go to the fuel tank? Is this just a recirculation line like found on fuel-injected autos?

I've had to replace my mechanical fuel pump with one I got from Eastern Surplus (supposed to be NOS, it looks to be rebuilt, not what I would consider NOS because its obviously been apart--subject for another time), the one I'm replacing is an AC flat top, ES' is not a flat top, the plumbing is slightly different so I'm trying to find fittings to make another fuel line from pump to carb.

Cbrinker
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Re: Carburetor Fitting

Post by Cbrinker » Sun Mar 17, 2019 7:06 pm

The other line is just a return line back to the tank. I learned the hard way that if that return line is not there or is clogged the mule will flood with fuel and not run right or at all

muleman7
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Re: Carburetor Fitting

Post by muleman7 » Mon Mar 18, 2019 7:04 am

I have the rebuild kits for the AC flat top pump. You may have gotten an Airtex pump that can be used on the mule but was the pump on the genset engines. It uses the same brass fittings as the AC pump but the humps will interfere with putting in the bottom air horn screw. Using the same fittings you will use the same fuel lines.

You do not need to remove the AC fuel pump from the engine to rebuild but may have to push carb back slightly to remove 4th screw. Remove the top and body then push down on the diaphragm and turn 90 degrees to remove. Install new diaphragm in reverse order.

AC flat top pump kit

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Rebuilt AC flat tip pump

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Airtex fuel pump used on the genset engines but can be used on the mule engine. I have these NOS New for $40.00

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Speedracer
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Re: Carburetor Fitting

Post by Speedracer » Mon Mar 18, 2019 10:46 am

Cbrinker wrote:
Sun Mar 17, 2019 7:06 pm
The other line is just a return line back to the tank. I learned the hard way that if that return line is not there or is clogged the mule will flood with fuel and not run right or at all
Well, it ran OK without the fuel tee before the fuel pump diaphragm started to leak. It actually ran OK but I smelled gas so shut it down, I think I caught it before too much gas went in the crankcase. It does run rich.

Since pumps don't like to be dead-headed, or close to it, I'm wondering if without the tee my fuel pump will fail prematurely.

Somewhere down the road I will consider installing an electric fuel pump.

Chuck W.
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Re: Carburetor Fitting

Post by Chuck W. » Mon Mar 18, 2019 4:47 pm

Somewhere down the road I will consider installing an electric fuel pump.
You will STILL needs the vent line from the carb to the tank. Without it, you risk the very real chance to overfill the engine with gasoline and wipe the bearings. John Emery has all the fittings and lines to return your engine to the correct configuration.
Check your copy of TM 5-2805-213-24P, pages 8,9,10 and 11.
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