EFI fuel sending unit return line upgrade?

Fuel and Air Systems

  1. ChargerST

    ChargerST Well-Known Member

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    I have an EFI tank from Spectra (CR9AFI) which has a 3/8 feed and a 5/16 return line. I don't know why Spectra has such a small return as almost all fuel pressure regulators require a return line at least the same as the feed line...

    What would be the best way to replace the 5/16 tube with a 3/8 tube? hard soldering seems to be impossible as the electrical connector is too close.
    I think a bulkhead fitting and a fuel resistant hose inside the tank would be my best bet. What do you think?

    Here's a pic for clarification:

    SP197A1H_TOP_P04.jpg SP197A1H_TOP_P05.jpg
     
    Last edited: Jul 22, 2021 at 2:58 AM
  2. Darter6

    Darter6 FBBO Gold Member FBBO Gold Member

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    Back in 2000 I did a Duster with Fast fuel injection.A bulk head fitting is what we used.
    Back then you had to make up everything.
    Now this is just me, my thought, You won't have any problem just using the 5/16'' return.
     
    • Agree Agree x 1
    • furious70

      furious70 Well-Known Member

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      I would try it first, if you can't keep your psi down where you want it then you might have an indication of a problem
       
    • Darter6

      Darter6 FBBO Gold Member FBBO Gold Member

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      Also I would like to add that we were using 38 lbs injectors.
      What is yours ?
       
    • INTMD8

      INTMD8 Well-Known Member

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      Agreed. Highest amount of bypass (flow through return) is at idle. If you can set the fuel pressure a bigger return line won't change anything.

      Years ago I built a fuel injected Malibu with over 600hp. Had a 5/16 feed and 1/4 return with zero problems.
       
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