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Fuel Pumps

Discussion in '1965-1970 Shelby Mustang GT350 & GT500' started by grm, Jan 21, 2008.

  1. grm

    grm Member

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    Hi Shelby Forum Members,

    I have a question regarding fuel pumps. I have an electric fuel pump on my '65 Shelby now. I am going to go to the mechanical type. If I disconnect the electric pump at the fuse box, can I just leave the electric pump in place so as not having to splice my gas line?

    If the answer to this is "yes"...will this place unnecessary drag on the mechanical pump...having to pull the gas through the non-working electric pump?

    Thanks for your thoughts.

    grm
     
  2. Shelby~gt350#3000

    Shelby~gt350#3000 Well-Known Member

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    I dont think the car will get fuel past the electric pump simply by "sucking" it from the mechanical fuel pump. Most pumps incorporate a roll over valve which eliminates fuel from traveling past the pump while being in the "off" position in the event of a roll over or car accident. The only way the fuel can flow is when the pump piston runs. If im wrong someone correct me. Hope this helps
    Jim
     
  3. Shelby6t7

    Shelby6t7 Well-Known Member

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    GRM;

    It's a simple switch back to mechanical, why go through all that other trouble. All you have to do is replace the tank to pump, and pump to carb fuel lines. It's a couple of hours work at most

    Kenny
     
  4. grm

    grm Member

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    Kenny,...Wouldn't it be easier to just remove the electric and splice the fuel line?
     
  5. grm

    grm Member

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    If I were to put a new fuel line in, how does it hook up to the gas tank? Do you have to drain it first?

    grm
     
  6. steveshelbymustang

    steveshelbymustang Well-Known Member

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    I'll post this photo that may help you. You can see the electric pump is disconnected and either end of the line is just spliced together. Depending on where your pump is mounted most electric pumps won't interfere with fuel flow. Most pumps are to increase pressure and lighten the load of the mechanical pump.
    [​IMG]

    Hope this helps
     
  7. grm

    grm Member

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    Thanks Steve...A picture is worth a thousand words. This really helps!\
    Greg
     
  8. grm

    grm Member

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    Anyone out there know for sure if the 3939 S was replaced by the 4009 S? Does the 4009 S look like the 3939 S?...I mean "button" on top and a white fuel filter canister below?

    I also understand that the 4009 S is a double spring just like the 3939 S...is that correct?

    grm
     

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