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I am going to put a new fuel pump in my car, the old one quit. Question, the new Holley has only an "in" and "out" on the pump. The other pump had in and out plus the out for the return line back to the tank. I know I have asked this one before, but do I need to have that return line , and what is the purpose of it :confused:
Have you ever heard of vapor lock? well the return prevents heat soak starting problems. also the return makes for steady fuel pressure instead of the pump pulses bouncing a pressure gauge like in a none return system
I'm not up on everything. So I can't say if it's good or bad. But it seems like mine isn't either because when I open it up to put in gas on a hot summer day like today the tank vents off pressure. I have never had a problem in the 12+ years that I've owned this Vette. I'm using the stock return type pump. With a light weight pump rod because I rev it up every once in awhile.
Anybody else have ideas on if the Holley pump is ok with plugging off the vent tube to the tank?
I am using the the setup you describe with the chrome mechanical pump. I also was a little worried about blocking off
the return line, but have had no problems whatsoever. Have fuel pressure gauge that shows a rock steady 9 psi. It
seems to feed my 383 quite well with a 780 cfm Holley.
Seems like if you have a Holley carb, then blocking the return line will have no negative effects. Mainly due to the large fuel bowls on a Holley.
With a Qjet, and the return line blocked, you will almost always get a vapor lock problem. Qjets have a very small gas bowl compared to a Holley, and it is also central in the carb., less chance to cool.
From: Just because I'm paranoid doesn't mean people aren't out to get me...
St. Jude Donor '09
Re: Fuel pump question (467-Ratman)
When I bought my '70, Bubba had already removed the return line(either that or my '70 is an LT-1 in disguise). I replaced the pump with an LT-1 pump ($19) because I had no return line. I didn't like the look of the AC Delco pump so switched to a Chrome Holley and run a steady 8psi.
I have experienced no vapor lock problems with this setup.