Fuel return options
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Fuel return options

  1. #1
    AKA Blownjet 468 Blowncat 509's Avatar
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    Default Fuel return options

    Hey guys, haven't been on here in quite a while ( lake has been empty, bought new house, etc) anyways, getting boat back together, and am trying to figure out the simplest way to run my fuel pump bypass/ return line. Have an Imco super fuel valve, but it's only a 3 port model, and I'm not going to buy the six port. Can I just weld up a 45* merge out of some 3/4 aluminum pipe, and put a check valve on it, and go back into the low press. Side of the pump? Thanks, open to ideas,


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  3. #2
    AKA Blownjet 468 Blowncat 509's Avatar
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    Don't everyone answer at once,...


    Out With The Old, In With The New.......Goodbye Blinding Acceleration, Hello Sustained High Speed (in comfort)

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    Or Seth, either one Budweiser's Avatar
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    So, you've got two tanks, a tank selector switch, yet no way to select where the return dumps.

    I'm not too sure about exactly how much of a "bad idea" it is to simply run the return to the low pressure side of the pump, but it's been said that it can heat the fuel. Not sure if there's another reason. I can't think of one. I'd be half way inclined to try it myself and see what's what. However, I wouldn't want to suggest someone else guinea pig the situation.

    You may be able to run the return to a "T" or "Y", each leg run to a respective tank, with an on/off solenoid in each leg of the return. Where it blocks return flow to the tank that's not being drawn from.

    Others have had success with omitting the tank selector switch altogether and just "T" the inputs from the tanks to the pump and "T" the return out to the tanks, keeping the hose lengths as close to equal as possible. I could see that putting check valves between the tanks output and the "T" would prevent flow from one tank to the other and the pump would automatically draw from the tank that's fullest (or at a higher level, if the boat lists a bit).
    Last edited by Budweiser; 05-18-2017 at 11:48 AM.

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  6. #4
    Senior Member ol guy's Avatar
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    Quote Originally Posted by Blowncat 509 View Post
    Hey guys, haven't been on here in quite a while ( lake has been empty, bought new house, etc) anyways, getting boat back together, and am trying to figure out the simplest way to run my fuel pump bypass/ return line. Have an Imco super fuel valve, but it's only a 3 port model, and I'm not going to buy the six port. Can I just weld up a 45* merge out of some 3/4 aluminum pipe, and put a check valve on it, and go back into the low press. Side of the pump? Thanks, open to ideas,
    Okay i will chime in. Remove all regulators on the in side and use a barrel valve to return to the tanks. Get constant fuel pressure at 7.5 to the carbs dump the rest of the fuel back to the tanks with a barrel or bypass valve.Basic M.F.I plumbing. It works out to be a constant fuel pressure system as injectors do with a lower pressure. Not rocket science but over looked by many. MARK
    Last edited by ol guy; 05-18-2017 at 07:04 PM.

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    my return goes to my remote fuel/water separator, works great
    1990 ultra 21' open bow. 509, American turbine Jet

  8. #6
    Senior Member Hass828's Avatar
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    When you lift off the throttle-- and the boat starts to decel, the fuel system will get a gulp of air and just sit there trying to recirculate it.
    Return needs to go back to the tank.
    My opinion is-- either do it with valves or buy the 6 port. JMO.
    "if we keep doing it the same way we always do..we will always get the same results"
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  9. #7
    LP-25.com Infomaniac's Avatar
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    I plumb dual tanks together with a "Y" block and return to the top of the "Y" block. If you want to isolate tanks you can install a shut off valve individually before the "Y" block and return is not affected.
    If For Some Reason I Do Something Worthy Of Recognition. God Provided The Ability And Deserves The Credit.


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