Fast efi fuel pump with 2 tanks---help!!!

Discussion in 'Tech Info' started by 78 Ford F150, Jun 17, 2012.

  1. 78 Ford F150

    78 Ford F150 Junior Member

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    Ok guys, I need your help with my EFI fuel pump setup. Here's what I'm working with...

    I have a 78 Ford F150 that I'm putting a 460 in. I wanted to convert it to fuel injection so I purchased the FAST EZ EFI throttle body fuel injection setup. I purchased the master kit, which included the EFI fuel pump. The problem is the system is set up for 1 gas tank and my truck has 2 gas tanks. The instructions state that the fuel pump needs to be mounted as close to the gas tank as possible, no more than 20" away. This means that my rear tank will be too far away for my fuel pump to operate without damaging or burning it up.

    So my solution is this (and this is where I need your help and advice, so if I'm wrong, please correct me)...I need to install a separate (secondary) fuel pump and mount it back by the rear tank to pump fuel up to the FAST fuel pump. I will mount the FAST fuel pump in front of the "Y" junction that switches to the different tanks. If I do this then I don't want the rear secondary pump running while I'm not using that tank. So my solution to this is to wire the secondary pump to turn on when I switch the toggle switch on the dash from the main tank to the Auxiliary (rear) tank. Am in on the right track here? Will this work?

    Another question regarding the PSI on the secondary fuel pump....what psi fuel pump do I run since this pumps ONLY job is to pump fuel from the rear pump up to the FAST EFI fuel pump, which will then take over duties of supplying the throttle body???? The FAST Fuel pump is to be set at 43 psi (with a fuel pressure regulator). I don't need a 43 psi secondary pump do I? Will any psi fuel pump work as long as it's not more pressure than the FAST fuel pump? What if I used an electronic fuel pump that was only 4-7 psi, that is used for carburetors? Would that work or do I need a EFI fuel pump that pumps the same amount of psi as the FAST fuel pump?

    As for the return style fuel system, I need to run a return fuel line to both tanks so I don't pump returned gas into a full tank that I'm not using. So my train of thought here is to install a "Tee" in the return fuel line and run it to both tanks. So if one tank gets full from return fuel, it will be forced to feed into the other tank....Am I on the right track here? Will this work????

    I have been asking these questions to the staff at FAST and they aren't much help because he states that he's never experience a dual tank setup installation so he's not sure how to do it. Also, it's my assumption that they don't want to advise me on how to install it and then have something go wrong with the risk of being held legally liable. Not that I would do that, but they just have a CYA attitude, which I don't blame them. So this is why I need your help....Thanks..
     
  2. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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    My opinion only, no liability expressed or implied.

    My take would be:

    The "no more than 20" inches" away should be for the FAST fuel pump's suction side.
    More than that would cause undue wear and tear
    on the pump motor trying to draw fuel from a "main" tank.
    The FAST pump's pressure side could pump fuel a long distance at 43psi.

    Forget the idea of a low psi pump to feed the FAST pump. Mount the FAST pump less than
    the 20" specified to the designated "main" tank. You will have to run a switched power
    circuit to the FAST pump mounted at the tank, not ACC (accessory) but RUN only. Using a ACC power would run the pump
    even if you were only sitting there listening to the radio and not running the engine.

    I would concentrate on a one tank method, to keep it simple just use one tank for the EFI system including the fuel return line.

    You could use the second tank as a reserve fuel supply with a manually
    switched pump to empty it's contents into the "main" tank,
    the one being used with the FAST EFI system, with a "T" type fitting at the filler neck.

    Forgetting to turn off the manual pump after it drains the reserve tank could cause it to burn the pump up also.

    Accurately working fuel sending units in both tanks would be a must in this application.

    I have the old school dual tank setup manually switched on this 1974 F100 FE 360 2V.

    [​IMG]
     
    Last edited: Jun 17, 2012
  3. cowboy

    cowboy Sheriff Staff Member

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    ^agreed. I like the idea of just using the main tank and using the second to pump to the main.
     
  4. Big'un

    Big'un BillyBadAss

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    im with these guys ^^^^ my 77 i just dont away with the front tank period
     
  5. 78 Ford F150

    78 Ford F150 Junior Member

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    That's a real good idea. I never thought of that. That sounds alot easier to wire and plumb than the way I was thinking of doing it....Thanks for the idea.
     
  6. Big'un

    Big'un BillyBadAss

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    No prob man , stick around with us and post some pics of your truck , i need a fellow dentside on here
     
  7. 78 Ford F150

    78 Ford F150 Junior Member

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    Had another question/thought....if I just pump fuel from the rear tank into the main tank, then I don't need a high pressure electric fuel pump, correct? I could get away with using a carbureted efi fuel pump at 4-7 psi??? Right???

    Let me figure out how to post pics and I'll post some for ya...
     
  8. Roush PSD Interceptor

    Roush PSD Interceptor Straight Piped Diesel Staff Member

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    Using the FAST EZ EFI throttle body I'd say the requirements for it are
    43 psi to accurately fire the injector/injectors in the throttle body itself.

    That system reminds me of the Holley PRO-Jection system when it
    first came out.
     
    Last edited: Jun 17, 2012
  9. 78 Ford F150

    78 Ford F150 Junior Member

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    I wasn't talking about the pump that feeds the throttle body, my question was regarding the fuel pump used to pump fuel from the rear tank into the main tank to fill it up. Can I use a low pressure (4-7 psi) carbureted pump just to pump fuel from one tank to the other tank? It doesn't have to be high pressure does it? Logically, I wouldn't think it would have to be high pressure, but just want to make sure.
     
  10. cowboy

    cowboy Sheriff Staff Member

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    I think you would be alright with a low pressure pump from the rear to the main.
     

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