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Technical Electric fuel pump

Discussion in 'Traditional Hot Rods' started by robert graves, Oct 15, 2020.

  1. robert graves
    Joined: Nov 2, 2018
    Posts: 74

    robert graves

    I’ve heard you can run a low volume electric fuel pump directly to the mechanical one on a flathead v8 , I’m not getting enough pressure to run well by having filters in the line to protect my carbs 1/2 psi is all I’m getting through the filters , and no I don’t want to remove filters
  2. AngleDrive
    Joined: Mar 9, 2006
    Posts: 827

    from Florida

  3. 51504bat
    Joined: May 22, 2010
    Posts: 2,162


    I'm running an electric pump mounted near the gas tank on my '39 p/u that is converted to 12 volts. I use it to prime the carbs after it sits for a while or in case of vapor lock. No issues with using it along with the existing mechanical pump. I do run a pressure regulator after the mechanical pump set at 2 1/2 pounds. What pressure is the pump putting out by itself?
    olscrounger likes this.
  4. TrailerTrashToo
    Joined: Jun 20, 2018
    Posts: 725


    1. Electric fuel pumps come in several pressure ranges - Start with what is the proper pressure for your carbs?
    2. If the diaphragm on your mechanical fuel pump fails, the oil quickly gets diluted with gasoline - hard on the bearings.
    3. Are you sure that you do not have a clogged pickup in the gas tank?

    I have done this, but only as a temporary measure, due to the potential of diluting the oil. Long term solution is two choices:

    1. Fix your fuel system to work properly on just a mechanical pump
    2. Bypass the mechanical pump and fit a proper fuel pump - Several issues need to be addressed, as the pump should be close to the gas tank and lower than the gas tank, fuel pressure to natch the carb specification, pre and post filtration, wiring (and fuse), rubber hose sections need to be compatible with ethanol, etc.

    p.s. other valid answers above
    warbird1 and jim32 like this.

  5. squirrel
    Joined: Sep 23, 2004
    Posts: 46,907


    that's much pressure is there before the filters? And what kind of filters are they?

    I knew filters could reduce flow, but not pressure.
    Pist-n-Broke, firstinsteele and XXL__ like this.
  6. fortynut
    Joined: Jul 16, 2008
    Posts: 993


    First off, since your question lacks details pertinent to a good answers, you need to consider what kind of voltage you have? The main reason, in my experience, fuel pumps on Flathead Fords crap out is because the lobe on the cam goes flat over time. To run pressure into a pump that has marginal to no effect on moving fuel, therefore, is a waste of resources. There was a time when you could use a twelve volt battery in a six volt system if the center of the battery could be tapped for six volts. I won't suggest step down resistors because the ones I have experience with generate too much heat. In my experience those who want to keep driving their cars on today's roads grit their teeth and change over to twelve volts. Alright, with all that out of the way, make damn sure the basis of your problem is not crap coming out of the fuel tank. With fuel delivery and spark, you need to back up to basics and think logically. If it has rust scale that comes out, have it boiled out and sloshed with sealer. Put your electric fuel pump as close to the tank as possible. Make sure, here, that it is insulated against transmitting any sound through the frame (where it should be mounted) because there is nothing more annoying, except a woodpecker in a tree next to the window where you're sleeping late, than the irritating vibration from a damn electric pump --- as you will then think of it. In order to know what kind of pressure comes out of the regulator you need a pressure gauge. The parameters of how much pressure are needed depend, of course on the carburetor(s) you are using. My sketchy account only gets you so far but I hope gives you some basic ideas of the methodology needed to visualize the problem and a solution. Thank you for your time.
    TrailerTrashToo likes this.
  7. Is it maybe just time for a fresh in line filter?
  8. I should have asked where your Filters are in the line. You say "filters" as if there is more than one.
  9. JeffB2
    Joined: Dec 18, 2006
    Posts: 8,493

    from Phoenix,AZ

  10. I had the similar issue with stock V8 in my ‘51 Ford. I tried to add an inline filter before the stock fuel pump when I replaced a failed fuel pump.Engine would not run. Removed the inline filter, engine ran fine using the stock glass sediment bowl / pump only.
    I have to prime carb. if car sits for longer than 5 days.

    Sent from my iPhone using The H.A.M.B. mobile app
    squirrel likes this.
  11. solidaxle
    Joined: Jan 6, 2011
    Posts: 488

    from Upstate,NY

  12. Doublepumper
    Joined: Jun 26, 2016
    Posts: 655


    All of the Carter pumps I've installed (only pump I use), I used their optional quiet pack (18-14U). The rubber cushions work very well for keeping the pump rattle down to a minimum. Just a slight thumping that can't be heard with the engine running. I recommend using them.

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