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Thread: Fuel sending unit question

  1. #1
    Junior Member
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    Fuel sending unit question

    Like to get some advice…. Wish I had more experience here.

    Going to run a 383 stroker with a Holley Sniper EFI. Spoke to Holley and their recommendation is to run all 3/8” fuel lines (supply and return). I did. Now looking at return on the sending unit and it is a 1/4 inch pipe on the sending unit. Seemed to be a “restriction”. Holley recommended to change it to 3/8” pipe and suggested the return tube should go down to about 1” from the bottom of the sending unit towards the bottom of the tank. The 1/4 inch return pipe in the sending unit extends about 3/4 inch below the top of the sending unit so it would have to be extended 6 plus inches.

    So, here are my questions…

    1- Is this a concern and has anyone run into problems with the 1/4 inch return on the sending unit for a 383 / sniper EFI configuration when rest is 3/8” fuel lines?
    2- Anyone do anything to increase volume on the return pipe of the sending unit and if so what did you do? E.G. drill out 1/4 tube and weld in 3/8”?
    3- Do you need to extend the return deeper into the tank regardless the configuration and if so what did you all do?

    Hopefully I am just thinking about it too much ;-)

    Thanks in advance all.
    John

  2. #2
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    I have the exact configuration 383/Sniper but I went 3/8 all the way, I used a Boyd Aftermarket tank. The advice about the return location low in the tank is spot on, that will avoid cavitation. JMHO

  3. #3
    Senior Member gbranham's Avatar
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    I replaced the Roadster kit-supplied fuel pump hanger with the Pro-M 87-93 Mustang Race hanger. It has 3/8" feed and 3/8" return fittings, both -6AN. It also has a return extension, to ensure return fuel doesn't cause cavitation.
    High Flow Fuel Pump Hanger for 1986 – 1997 Mustangs (promracing.com)
    Built an early MkIII years ago, sold years ago.
    Got Corvettes out of my system, and now back after 18 years to build a MkIV.
    MkIV Complete Kit Ordered 4/18/23, Delivered 7/11/23, 427 Stroker, Holley Sniper 2, Hyperspark, TKX, IRS, Wilwood Big Brakes
    Here to learn, contribute, and have fun!

  4. #4
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    Appreciate the info…thanks!
    John

  5. #5
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    Great videos with the link! Thanks for the info!

  6. #6
    Senior Member gbranham's Avatar
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    You bet. Happy to help.
    Built an early MkIII years ago, sold years ago.
    Got Corvettes out of my system, and now back after 18 years to build a MkIV.
    MkIV Complete Kit Ordered 4/18/23, Delivered 7/11/23, 427 Stroker, Holley Sniper 2, Hyperspark, TKX, IRS, Wilwood Big Brakes
    Here to learn, contribute, and have fun!

  7. #7
    Senior Member MPTech's Avatar
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    x2 Greg's suggestion on the Pro-M Hanger. All your problems resolved and keep your existing fuel tank.
    I'm running a fresh 347 build with Sniper EFI all 3/8".
    F5R #7446: MK4, 302, T5 midshift, 3.55 Posi IRS, 17" Halibrands
    Delivered 4/4/11, First start 9/29/12, Licensed 4/24/13, off to PAINT 2/15/14!! Wahoo!

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