Electric fuel pump

[stallion112]

I'm running an AC Delco EP12S electric fuel pump rated at 5 to 9 psi with a Holley 750 cfm. The pump is supposedly good for carbs without needing a fuel regulator. Is anyone else running this fuel pump with a carb and do you have problems related to too much fuel pressure?

Also, some regulators are available without needing a return line back to the fuel tank. Do these really work or are you better off just going with a regulator that uses a return line?

[Tim Brewer]

I'm not running that type of pump, I use a Mallory with a regulator. With that type of pump, how do or would you know you had X ammount of pressure to the carb? You can have problems with too much pressure, flooding engine etc. All regulators will work without a return line, you don't need a return line unless you are using fuel injection, you just plug up the extra ports on the regulator that arn't being used.
Tim

[Tommy]

My car was equipped with a Holley Red (internally regulated) fuel pump. It worked fine for cruising, but was a problem at the track on hot days. This pump has a spring controlled valve that diverts fuel leaving the impeller back to the intake side of the pump when pressure to the output side exceeds about six psi. That means the same small amount of gasoline will circulate repeatedly through the impeller until the engine demands more fuel. Under the heavy demand of full throttle track use, the pump would get hot and the fuel recirculating through it would absorb enough heat to boil and cause vapor lock. I rebuilt the pump with a heavier spring to keep the diverter valve closed and added an adjustable fuel pressure regulator with a return line to the tank. This arrangement keeps fuel from staying in the fuel pump long enough to get hot and vaporize. .. I hope this helped answer your question.