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Old 09-17-2021, 08:47 AM
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Tom Vaught Tom Vaught is offline
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Join Date: Dec 2001
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Quote:
Originally Posted by steve25 View Post
Do you realize that when the electric pump is not running that the pump is then a great restriction and that if the fuel is hot enough at that point that the difference in pressure can make for vapor lock taking place right there at the pump?
Holley pumps for sure need the fuel "by-pass" circuit (LIKE SOME CARTER FUEL PUMPS OFFER), because the moveable vanes move outward,stick, and then block fuel flow. It only takes one or two sticking vanes to restrict the fuel flow to the mechanical fuel pump. Same deal with any pump that uses Vanes that move outward when the pump is on. Even with the vanes retracted, there is a restriction. The BY-PASS CIRCUIT solves that issue. I use bypass valves with a large "sealing ball" to reduce back flow when the electric pump is on.

As was mentioned, you can buy that bypass system with the pump in some carter pump applications. Not sure of their by-pass flow area.

Tom V.

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