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What's The Purpose Of Using A Mechanical And Electric Fuel Pump?

Discussion in 'Early CJ-5 and CJ-6 Tech' started by Matt Mitchell, Nov 30, 2018.

  1. Jan 12, 2019
    willie2323

    willie2323 Purchased new

    Phoenix, Arizona
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    Dec 10, 2009
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    Yes, this is the reason on my 53 Ford the previous owner installed an electric fuel pump upstream of the (high mounted) mechanical pump with a bypass line to allow the mechanical pump to pull from the tank without the electrical pump. The electrical pump is only used to start the engine.

    One caution on using an electric fuel pump hard wired to 12 volts with the key on, is in an accident if the fuel line is ruptured between the fuel pump and the engine...nothing to stop that pump from emptying the fuel tank.
     
  2. Jan 13, 2019
    Matt Mitchell

    Matt Mitchell Playin w/My Willy

    Idaho Pan Handle
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    Nov 4, 2018
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    I have a switch wired in to control the pump.
     
  3. Jan 13, 2019
    willie2323

    willie2323 Purchased new

    Phoenix, Arizona
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    This will be sufficient should you be conscious in the accident and remember to shut it off but if you are knocked out or forget and the fuel line is ruptured, this is the issue. I think some have addressed this issue with an electric fuel pump but cant think of the solution. I was running an electric fuel pump but have gone back to mechanical for this very reason...YMMV.
     
    Matt Mitchell likes this.
  4. Jan 13, 2019
    timgr

    timgr Jeepin' Nerd Sponsor

    Medford Mass USA
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    There are a couple of ways to approach this. One is use a switch or relay connected to the oil pressure of the engine. No oil pressure, no fuel pump, except when cranking. You can add a manual override as a push button on the dash that runs the fuel pump when there's no oil pressure. There's also a module available that runs the fuel pump for a few seconds after the key is on, and relies on the engine oil pressure thereafter. Search and you'll find such products.
     
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  5. Jan 14, 2019
    NCRenII

    NCRenII yellow fever Sponsor

    Far Nor Cal
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  6. Jan 14, 2019
    Alan28

    Alan28 Sponsor Sponsor

    Ch√Ętillon en...
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    Not a bad idea, just to say that it must be well installed.
    After some days, my carb is not full and it takes some time and battery to start.
    So I use the lever on my manual pump before starting the engine, it works perfectly.
    I suppose that, adding an electric pump, you just have to seat, put electric system in action turning the key, wait some seconds and all is full.
    I understand that the electric fuel pump is not well adapted, there can be problems.
    Everytime we had something on a car, we add a problem...:rockn:
     
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  7. Jan 14, 2019
    70cj5134f

    70cj5134f Member

    East Tn
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    Aug 18, 2018
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    I use a switch that lights up when on, easy to remember to turn off,
    Also my inline pump can be heard , and its only used for startup.
     
    Alan28 and Matt Mitchell like this.

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