edelbrock fuel pump at 3 psi?

Discussion in 'Technical' started by garrettmuir1227, Jul 27, 2014.

  1. garrettmuir1227

    garrettmuir1227 (Almost) Certified to Work on Your Porsche

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    so i ahve been having problems with my car since i added my holley carb. i also got a new pump at the same time and totally forgot about it. added a fuel pressure gauge today and the fuel pressure is at 3 psi! it is supposed to be at about 8. what would cause this preoblem??
     
  2. scooper77515

    scooper77515 No current projects.

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    You need 4-5 psi for most holleys and edelbrock carbs.

    What brand/model is the pump? Many are adjustable to get the correct psi for your carb.
     
  3. garrettmuir1227

    garrettmuir1227 (Almost) Certified to Work on Your Porsche

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    It is an edelbrock mechanical pump
     
  4. scooper77515

    scooper77515 No current projects.

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    Is it this one?

    [​IMG]

    This is the 110 gph pump, and it should be pushing 6 psi. If not, no adjustments that I know of. Might have a torn diaphragm.

    Of course, it could also be an obstruction or clogged fuel filter somewhere up stream...
     
    Last edited: Jul 27, 2014
  5. maverick75

    maverick75 Gotta Love Mavs!

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    What size fuel hose are you running?
     
  6. garrettmuir1227

    garrettmuir1227 (Almost) Certified to Work on Your Porsche

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    3/8 hose I'm pretty sure
     
  7. Bryant

    Bryant forgot more than learned

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    unless you have a restriction in your fuel system the pump is not doing its job. you could have a clogged up sock in the tank, a collapsed rubber hose, a crushed steel line, something plugging up a fuel line, a plugged up fuel filter.

    i would get a gas can full of fuel and put a hose from the pump inlet to the gas can and start it to see if it will make the proper fuel pressure. if it does then you need to look for the restriction, if no then you need a new pump or see if you can rebuild the edelbrock pump.
     
  8. garrettmuir1227

    garrettmuir1227 (Almost) Certified to Work on Your Porsche

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    Okay I'll do that. Thanks for the tip!
     
  9. scooper77515

    scooper77515 No current projects.

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    Another thing to keep in mind, cheap fuel pressure gauges are not always accurate. I have a high-dollar gauge right after my regulator, and another cheapie one just before the carb, and they are always a psi or 2 different. If I recall correctly, my cheapie one reads 4-5 and my high-dollar one reads 6.
     
  10. baddad457

    baddad457 Member

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    You didn't say what the problem you're having is. Pressure isn't as important as flow. You can have 3 psi pressure and still have the flow to supply the carb. The reason you don't use a high pressure pump with a carb is the only thing that keeps the flow into the fuel bowl in check is the needle/seat which is operated by the fuel float. Too much pressure will sink the float and flood the carb's bowl. The pressure is there only to push fuel into the bowl as the float opens the needle/seat valve. It takes very little pressure to accomplish this.
     

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