Hey guys and gals,
I am setting up my fuel system for my 1950 F3 with a 302, auto trans and Holley carb. I am going to use the Red Holley electric fuel pump and am wondering how it knows when to stop pumping fuel to the carb. Is there an internal circuit in the pump? I got a guy telling me that I will need a carb with a return line to the tank in order to make it work, otherwise it will constantly flood. He tried to equate it to the manual cam driven fuel pumps. He said they have a return nipple on them, but every manual fuel pump I have ever seen for 70-80s Chevys or Fords have had only two, one inlet from the tank and one outlet to the carb. Can you folks tell me if I am mistaken with my plan? I will have the electric pump mounted as close to the rear frame mounted tank as possible. I will have a filter between the tank and the pump. Then I will have steel 3/8 fuel line running up to the front of the truck with a short rubber fuel line connecting to the carb. I pulled the fuel line from a 75 F150 with a 302. It has been cleaned out and is ready to go. I have already installed a rollover/vent valve for the rear tank. Any help will be appreciated.

 

I run a holley blue pump on my mustang with no return, no problems.

I run a carter electric pump on my 5.0 ranger with no return, no problems.

I would thing the float on the carb should act as the stopper, but I am no expert, just my personal experience.

 

See this thread for mounting requirements, and reasons to run a return; not necessary, but better: https://www.ford-trucks.com/forums/1...lp-please.html

Also see notes from Holley's website for this pump below

 

I am going thru the same thing about setting my fuel system up for the third time. Ross is guiding you to a good thread about what problems I have had dealing with this issue.

Should have something figured out by this coming weekend. I have been following the advise of Ross and AX and it is starting to look like this problem might work it's way out.

Dennis

 

I'm real curious about the Holley statements that the Red pump isn't suitable for alcohol. Have either of you checked with Holley to see if that includes gasohol (E-10)? With E-10 virtually law, I don't see how they could make a pump that won't handle it.

 

A return line isn't necessary unless you have a big problem with vapor lock. If you install your fuel pump below the level of the gas in your tank and as close to the tank as you can get it, it will be a "pusher" system. The fuel under pressure is less likely to vapor lock than fuel that is under suction (as in a "puller" system that has a pump under the hood and sucks fuel the entire length of your truck). Be careful to make sure that the pump and filter isn't vulnerable to road hazards, so on the frame is usually a good spot.

The Holley carb should have a spec for the fuel pressure, and you can set the regulator on the red pump to whatever Holley recommends for their carb.

When the float bowl is full, the float valve in the carburetor will shut off the flow of fuel a lot like the float valve in the back of a toilet. As fuel is consumed, the valve will open again letting fuel flow into the float bowl. It is cyclic, and the pump is designed to pump against the closed system without damage. By the way....Holley carbs have a plug you can pull out that allows you to set the float level from the externally adjustable float valve. The fuel pressure will affect the level of the fuel in the float bowl because high pressures are harder to shut off....so the float has to rise a little more to get enough force to shut off the float valve.

If you find that you have a big problem with vapor lock, the return type system allows cool fuel to be continuously flowing through the system. I have never had to install one on a carbureted car or truck. The 302 should use enough fuel to keep some flow going through your single fuel line.

Dan

 

My experience with electric fuel pumps (in other applications) is as old_Dan suggests: - they pump until they produce the pressure in the fuel line to the carburetor for which they are calibrated. Some brands stop pumping at that point and cycle while some constantly tick over. As fuel is consumed from the carb, the float falls which reduces the pressure in the line from the pump. The float rises in the carburetor bowl when it is full and shuts off the flow, allowing the pressure in the line to rise again.

As a suggestion - if you have not thoroughly cleaned out your fuel tank, consider placing a filter AHEAD of the pump as well as behind - filters are cheap, pumps are not.

 

So after talking with the techs at Holley, the red pump is not adjustable and has been calibrated to work perfectly with my Holley carb. No need for a return line. As long as it is mounted near the tank and below the bottom of the tank it should work without issue.

Thanks for the inputs.

 

Even if you have cleaned the tank, AND replaced the lines, you absolutely need a good filter ahead of the pump. The Holley pumps come with a screen, which will protect the pump but a real filter is much better.

 

That's a good call.....I have a filter before the pump to protect the pump from debris in the tank, and one after the pump to protect the carb from junk that might come out of a failing pump.

Dan

 

One final note. I would suggest a safety switch to cut power in an accident.

 

Yep...got that covered. I forgot to mention, I am using the Holley 3 terminal oil pressure cutoff switch and their fuel pump wiring harness.