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Electric Fuel Pumps, Push vs Pull?

Discussion in 'The Hokey Ass Message Board' started by Boeing Bomber, Feb 17, 2011.

  1. Boeing Bomber
    Joined: Aug 5, 2010
    Posts: 1,079

    Boeing Bomber
    Member

    Just got a Hot Rod that the previous owner had installed a pulling Electric Fuel pump on. I've heard a Pushing one is better. Why?? and is an electric one any better than a mechanical one?
    Also... I've heard about running the power lead from the oil pressure switch. Okay, that makes sense if the engine dies, but any other good benifits to this?
     
  2. Gotgas
    Joined: Jul 22, 2004
    Posts: 6,935

    Gotgas
    Member
    from DFW USA

    Push. The way most electric fuel pumps are designed, they operate more efficiently that way. It also needs to be mounted lower than the fuel tank if possible so that it stays primed.

    It is okay to wire the pump through an oil pressure sensor. But with a carb'd car, the engine will continue to run for a little while after the engine loses oil pressure. All the carb really needs to operate is fuel in the carb bowl and there is plenty for that even without fuel pressure.

    I would wire it up with a modern inertia switch so that in the event of an accident, you don't have the pump dousing the accident scene with fuel.
     
  3. maniac
    Joined: Jul 11, 2005
    Posts: 539

    maniac
    Member

    They all sort of push and pull, I have one between the tank and carb, pulls from tank and pushes to carb. I don't have room for a mechanical one, so an electric was needed.

    As far as wiring to the oil pressure switch you want the pump to turn off in a wreck so it doesn't pump gas onto an already bad situation, there are switches for that, most new cars have them
     
  4. 53sled
    Joined: Jul 5, 2005
    Posts: 5,818

    53sled
    Member
    from KCMO

    whatever you do, make sure it will turn off without oil pressure, or an inertia switch, or both. Many a car have burned to the ground that way.
     

  5. Boeing Bomber
    Joined: Aug 5, 2010
    Posts: 1,079

    Boeing Bomber
    Member

    Tell me more about this inertia switch. is it something my NAPA guy would carry? I think I saw a schematic here somewhere. Thanx,
     
  6. maniac
    Joined: Jul 11, 2005
    Posts: 539

    maniac
    Member

  7. Boeing Bomber
    Joined: Aug 5, 2010
    Posts: 1,079

    Boeing Bomber
    Member

    WOW, thanx Maniac, I've used their wiring kits and they're the BEST. I'll give 'em a call
     
  8. newsomtravis
    Joined: Jun 1, 2009
    Posts: 562

    newsomtravis
    Member
    from pville, ca

    electric fuel pumps push, mechanical pumps pull......if its electric it needs to be as close to the tank as possible......and if you don`t believe me, just look at any new car with fuel injection......either right next to the tank, or inside of it......
     
  9. Mat Thrasher
    Joined: Nov 5, 2007
    Posts: 1,165

    Mat Thrasher
    Member

  10. And be sure to mount the electric pump low so it has a steady gravity feed for longest life.
     
  11. so...thinking of using FI-tech EFI . I am currently using an RCI 15 gallon tank with carburetor and mechanical SBC fuel pump..Tank has top mounted fuel outlet, fuel return, and vent fittings...no fittings on tank bottom at all. Question is: will an external push type rotary electric fuel pump mounted below the level of the tank and within a foot of the tank work with FI-tech set up? or do I take the tank out and carve a big hole in it and go with an in-tank unit? Not worried about noisey pump as the car exhaust is pretty noisy so would probably be a non-issue. Thanks...
     
  12. Blues4U
    Joined: Oct 1, 2015
    Posts: 5,314

    Blues4U
    Member
    from So Cal

    I don't understand the question. All pumps "push", or rather the mechanically move fluid in a direction, with a low pressure inlet and a higher pressure outlet. If the question, as I suspect, is more like "where should the pump be located, closer to the tank or closer to the engine, I don't think it matters much, as long as the supply line to the pump is unrestricted and gravity fed. Other than that, I think the shorter the distance between the output of the pump and the carburetor the easier it is on the pump.
     
  13. wvenfield
    Joined: Nov 23, 2006
    Posts: 5,226

    wvenfield
    Member

    The original question was asked 7 years ago and IMO the correct answer is "It depends on the application".
     
    Elcohaulic likes this.
  14. Actually I would not run the pump from the oil pressure gauge. An electric pump needs its own dedicated circuit. Put a crash switch in line ( like from a 90s Ford) if you are worried about it.

    Some electric pumps pull real well. I have an old Aeroquip pulse pump that you can mount on a fender well or the firewall real well. The more positive vane (pumps) are better pushers than they are pullers they want to be mounted close to and below the fuel source. Its not an exact science and sometimes you can fudge a little bit.

    Better or not better then a mechanical depends on a lot of things, a high performance electric pump will move a lot of fuel, most mechanicals do not move a lot of fuel. If you need a lot of fuel then you will want an electric. Or sometimes electrics are used when there is a space constraint, like when using a Hurst mount or chassis constraints like a really narrow chassis. In those instances an electric is "better".

    If you are using a stockish or mild motor a mechanical will probably suit you just fine. If I was running an electric already and it was working and the noise didn't bother me I would probably not trade it out for a mechanical. But that is just me if something works I leave it alone.
     

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