F-100 Holley 1940 carb

[2loud2old]

I have a '65 F-100 six. It has a Holley model 1940 carb. I have been having trouble starting after it sits for a few days. Seems that the accelerator pump is either dry or the linkage is not engaging. It has that strange triangular linkage with the three slots. If I pump my gas pedal and close the choke it will start. Once it starts it runs fine and starts easily until I put it away for a day or so and then I must fight to start it all over again. Had it rebuilt and the guy said it was "bleeding down" and to put on a fuel filter??? Any thoughts?

[40cpe]

It is not uncommon to have to prime the carburetor after sitting for a few days, especially with ethanol in the gasoline. Or the carb could be leaking some, too. You can test the carb by taking it off the manifold, filling the bowl with gasoline, and set it on a clean white towel on the bench over night. Gasoline will stain the towel. At least you will know which way it is getting out. Many of us have a flow-through type electric fuel pump back at the gas tank to re-prime the carb after sitting for prolonged periods.

[2loud2old]

Thanks for the reply.Not familiar with a flow through electric pump. I will investigate that option.I did find a fuel leak where the fuel line connects to the carb and tightened the connection. Haven't attempted to start the truck today. Will try removing the carb and setting it in the bench overnight.

[2loud2old]

I have read some forums and most recommend installing a flow through pump near the fuel tank to be used to prime the carb then shut off. Does the electric pump push fuel through the mechanical pump then fill the float bowl allowing you to then prime using the accelerator pump? Some run the electric pump in series and some run it as a parallel system. Any thoughts? Many recommend Airtex E8090 or Airtex E8016S(2.5-4.5psi)

[40cpe]

The airtex pump works well. It does push fuel through the mechanical and fills the carb bowl. Installing the pump in series works just fine. The parallel system requires more fittings and a check valve for no real benefit. Just get the pump that is compatible with your system voltage.

[dmsfrr]

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Originally Posted by 40cpe

. . .
Just get the pump that is compatible with your system voltage.

and fuel pressure, you won't need much (4 psi max ?) so it doesn't blow past the carb float valve.

.

[scicala]

Your rebuilder's idea of adding a fuel filter to keep the fuel in the carb from going away makes no sense to me. Even if it were possible for the carb to siphon the fuel backwards back into the fuel line it would be a rare thing and pretty much impossible with the 1940 carb since the fuel inlet valve is above the fuel level.


Sal

[2loud2old]

I think that he was implying that dirt in my fuel system was causing the problem.

[dmsfrr]

As fuel sitting in the carb evaporates the float valve will open. When that happens the fuel line up to the carb can drain down to the same level as in the fuel tank. There are check valves in the mechanical fuel pump but if they're tired or there's a bit of debris in there it can happen a little quicker.

Example: Put a soda straw in a glass full of liquid then cover the top with your finger. Lift the straw out of the glass and the liquid will stay in the straw until you remove your finger.

.

[2loud2old]

Something to think about. Thanks!