1984 F250 tank upgrades

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Glsawyer, Aug 6, 2018.

  1. Glsawyer

    Glsawyer Full Access Member

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    i have a 84 f250 4x4. i wm replacing the rear tank with a 38gl. i got a new sending unit with it but i noticed the factory system has 2 lines on the tank. supply and return. new sending unit only has a supply line. how to u make it work? i would like to not have a return to the rear tank if possible...

    im thinking return only to front tank. this would alow me to switch from a 6 port tsv to a 3 port. one line to selector from each tank and then to the motor. and just run the return line into the front tank without having to go threw the tsf.

    any thoughts?
     
  2. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Your idea won't work. If you only return to the front tank, you'll fairly quickly pump the front tank full and overflow it. All of the fuel that isn't burned by the engine is returned to the fuel tank. The slower your engine's running, the more fuel will return to the tank. Assuming that the front tank is stock, even if the front's empty, the rear tank holds twice as much fuel so it WILL over fill the front one. Remember, your stock supply line is 3/8" while your stock return is 5/16" for a reason. Most of your supplied fuel will be returned to the tank unless you're WOT. The only way that I can see that you MAY be able to do this is if you run a transfer line from the front tank back to the rear one so that when it gets so full, then it runs into the rear tank to keep from overflowing. If you're going to do this much work, why not just leave it stock? Aside from the highly expensive FSV.
     
  3. Glsawyer

    Glsawyer Full Access Member

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    wait.....is the smaller line the supply or the return
     
  4. Re3500

    Re3500 Registered User

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    Could u run ur return to the rear tank fill tube some how
     
  5. Glsawyer

    Glsawyer Full Access Member

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    a new selector valve is 80
     
  6. Glsawyer

    Glsawyer Full Access Member

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    id love to keep it stock but the new sending unit dosnt have a return port
     
  7. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    The smaller line is the return. You don't need as big of a line for the return as for the supply because there will never be as much fuel returned as there is supplied. The supply also has to be bigger to make sure that you'll have enough fuel to your engine at WOT. The return is flowing the highest percentage of the overall supplied fuel at an idle. Since the engine is only idling, there isn't as large of a volume being pumped through the supply line since the fuel pump is being worked slower due to lower engine RPMs. Again, I'm talking about the stock set up with the mechanical lift pump.
     
  8. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Sure, but then the front tank would return to the rear tank, bypassing the FSV.
     
  9. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    For a diesel? I'm pretty sure that they're higher. If not, I NEED to be buying one myself.
     
  10. Glsawyer

    Glsawyer Full Access Member

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  11. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    I'd bet that if you were to get a tank and sending unitfor a Bronco with EFI, it would. They also need to have a return line since the electric fuel pump is always pumping a large volume of gasoline.
     
  12. Glsawyer

    Glsawyer Full Access Member

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  13. IDIBRONCO

    IDIBRONCO IDIBRONCO

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  14. Glsawyer

    Glsawyer Full Access Member

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    hell i cant even find oem
     
  15. Glsawyer

    Glsawyer Full Access Member

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    i also cant fin a sending unit for the side tank
    '
     

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