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  1. #1

    Default Electric fuel pump on carburetor. Need help...

    Found out a little too late that the motor I ordered did not have an eccentric to run my mechanical fuel pump, so now I have to use an electric one. No big deal, but I am not sure what to do with the return line that used to be hooked up to the stock fuel pump. Was that line just used to pump excess fuel back to the tank? Can I just cap it off? I'm not sure if it was running fuel back to the tank of if the pump was putting air into that line.

    Anybody with a little knowledge on the situation please help!

    Thanks

  2. #2
    FEP Supporter Broncojunkie's Avatar
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    Wouldn't it be easier to just add the eccentric? And if you run an electric pump, I would suggest running a return on it. It's much healthier for the pump and generally works better that way.
    79 Pace Car - 331, t5
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  3. #3

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    Name:  lrs-9350mp_3888.jpg
Views: 206
Size:  11.2 KBthe little line above the fuel line that goes to the carb is the one I am talking about...

  4. #4
    Moderator wraithracing's Avatar
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    The return line in an EFI system is just that. Returns fuel to the tank. Some carb applications had return lines for the same reason.

    You can run an electric fuel pump with a carburetor. Your biggest issue will be making sure you run a regulator that keeps the fuel pressure at a level that is necessary for the carburetor to function properly. Generally around 5-7 lbs compared to 32-43 lbs for most stock EFI pumps.

    Although it might be a bit of a PITA at this point to disassemble the front of the engine to install a fuel pump eccentric, if your timing cover has the opening for one, that will still probably be the easier and cheaper route to go. Quality fuel pressure regulators are not inexpensive. You also want to make sure any rubber lines from the pump to the carburetor/pressure regulator are rated for the higher pressure. Normal fuel line is not and could burst from the additional pressure. Good Luck!
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Ongoing RestoModification
    1984 SVO Awaiting Restoration
    1986 GT Wrecked by PO, but still want to save!

    Current Capris:
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    1981 Capri Black Magic Roller Basket Case
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    1984 Capri RS T-top Roller
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  5. #5

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    Didn't even look before I assembled it

  6. #6

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    No efi. Car is a stock 83, been carburetor all of its life. I have a fuel pump designed for carburetors, only 7psi. I just need to know if said line is a return line, and if it is necessary.

  7. #7
    Moderator wraithracing's Avatar
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    I honestly don't recall the actual routing of the additional line on the stock fuel pump. I have the same setup on my 82 RS. Unfortunately mine was not running and missing parts when I purchased it. Hopefully someone can chime in and verify the actual connection of the extra line.

    I would bet you can run without the line as it was most likely emissions related, but again want to verify that before moving forward. I assume you are running the stock 4bbl carburetor?
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Ongoing RestoModification
    1984 SVO Awaiting Restoration
    1986 GT Wrecked by PO, but still want to save!

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Underway
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  8. #8
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    The regulator will have a return line.
    Not sure how to plumb it into the tank though.
    Still trying to figure that one out for my Fairmont wagon...

  9. #9

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    Hello. I had an 84 GT engine in my Pace Car and I swapped my stock fuel pump like the one pictured above with an Edelbrock pump. The Eddie pump doesn't have that little extra line port, just the inlet for the fuel and outlet to the carb. So that extra line that may be a return line back to the tank because I just have it tucked away and plugged up and the car runs fine. I'm guessing the Eddie pump doesn't require that return because it's already rated at 5-7 PSI normal operation. Also, when I check my tank under the car, there are two ports on the sending unit, 1 bigger and 1 slightly smaller. So I'm guessing the smaller line must be that return line.
    What's a little confusing for me is that I didn't think carbed applications had return lines back to the tank. My car had originally 4T engine, but yet the there are 2 lines running from the tank to the front.

  10. #10

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    I am running a electric holley fuel pump rated 5-7 psi and no return line. I just tucked the return line away and have had no issues in 7 years of running it that way. Just make sure you install a inline fuel filter before the pump and run the outlet hose right to the carb.
    Bob
    1967 mustang coupe -sold
    1967 cougar GT - sold
    1984 Mustang L 5.0L - Totaled
    1984 Mustang GT 5.0L
    2007 Mustang GT convertible ( wifes car)
    1997 F-350 powerstroke
    USMC Retired 1981-2001

  11. #11

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    Late answer but here's a suggestion, Holley carburetor adjustable fuel pressure regulator for systems with a bypass return line to the tank.
    https://www.holley.com/products/fuel...parts/12-803BP

  12. #12
    FEP Power Member Puter's Avatar
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    Quote Originally Posted by supercharged347 View Post
    I am running a electric holley fuel pump rated 5-7 psi and no return line. I just tucked the return line away and have had no issues in 7 years of running it that way. Just make sure you install a inline fuel filter before the pump and run the outlet hose right to the carb.
    Bob
    I've been doing this for many years on my 84. It's the Holley red pump. Cut a rectangle of radiator hose for an isolation pad and hung it off my rear bumper. Placed a filter before it. Ran a thick switched power wire (can't remember gauge) making sure that I fused it right after the splice under the hood and tied along the brake lines. I also do not use the vent line.
    84 GT
    85 GT convertible

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