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Thread: Decreasing Fuel Pressure

  1. #1

    Default Decreasing Fuel Pressure

    I have a in-tank fuel pump rated for EFI. I have replaced the old EFI engine with a blown 355cu in SBC with 2x4 carbs. I want to keep the in-tank pump if possible but it has too much pressure. Can I reduce the pump pressure by bypassing fuel with a pop off jet? Can set at 12 lbs returning it back in to the existing return line already there? Add a standard Holley regulator and then adjust the fuel pressure down to 5-7 lbs for the carb setup? Thanks Johnrodz

  2. #2
    Join Date
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    Quote Originally Posted by johnrodz View Post
    I want to keep the in-tank pump if possible but it has too much pressure.
    Yes, an EFI electric fuel pump can be used for a carbureted application.
    Listen to Doug Flynn @ :59 seconds explain how to use EFI fuel pump on a carbureted application:
    https://youtu.be/fMHQYxT-JOs?t=60 (Holley Fuel Pumps YouTube Video)

    EFI fuel pumps have a wide range of psi capability; you set the exact pressure you need/want.
    Electric fuel pumps only produce volume, the fuel pressure regulator creates the desired pressure.
    You must remove the EFI fuel pressure regulator and install a return type (bypass) regulator designed for 4.5-9 psi.

    Don't confuse psi ratings with what the pump is actually capable of.
    The psi ratings are for performance (volume) information only; they're not a pressure setting.
    Also, any EFI fuel pump will decrease volume output (GPH flow) as fuel pressure is increased.

    http://www.holley.com/types/Billet%2...ne%20Pumps.asp (Billet Electric In-Line Pumps)
    http://documents.holley.com/holleyfu...ems_chart1.pdf (Fuel System Selection Chart)
    http://documents.holley.com/flyer_ho...el_systems.pdf (Holley Fuel Systems Brochure)
    https://www.youtube.com/watch?v=fMHQYxT-JOs (Holley Fuel Pumps - Video 1)
    https://www.youtube.com/watch?v=6O2XTWH5xn4 (Holley Fuel Pumps - Video 2)
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