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Technical mechanical fuel pump for sbc

Discussion in 'The Hokey Ass Message Board' started by bodymanmp, Dec 29, 2022.

  1. 1971BB427
    Joined: Mar 6, 2010
    Posts: 9,816

    1971BB427
    Member
    from Oregon

    I've seen too many of all brands of mechanical pumps that had higher pressures than carbs can handle. And too many guys having flooding issues and rebuilding, or replacing carbs only to have the same issues still!
    I also always install a fuel pressure gauge on all of my builds so I can easily see what the fuel pressure is at a glance. These issues don't just happen with cheap pumps, or old pumps; they happen regardless.
     
    Deuces, saltracer219 and Kelly Burns like this.
  2. saltracer219
    Joined: Sep 23, 2006
    Posts: 1,170

    saltracer219
    Member

    I get it and totally agree. I do the same thing but my point here is that this never used to be a problem with quality U.S. made parts when people took pride in their work. There are not many parts to a mechanical fuel pump, it seems that they could get the spring tension for the relief valve within specs.
     
    Pist-n-Broke likes this.
  3. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 6,062

    2OLD2FAST
    Member
    from illinois

    Guess Edelbrock tech forgot about the internal valves in the pump ?
     
  4. gimpyshotrods
    Joined: May 20, 2009
    Posts: 24,513

    gimpyshotrods
    ALLIANCE MEMBER

    Stuck check valve.
     
  5. 54FISH
    Joined: Jan 10, 2011
    Posts: 421

    54FISH
    Member

    Ya think ? Even after it runs good for about 10 minutes ? I mean I gotta believe uour right ,it's gotta be in the pump .the tank & feed line is out of the equation , the outlet line from pump to carb is new. Thanks ,I'm thinking of going with a higher psi pump ( 6-7, quickfuel or holley) .but still want to know wtf is causing this . Have a good one bud & thanks very much!!
     
  6. impala4speed
    Joined: Jan 31, 2010
    Posts: 647

    impala4speed
    Member

    I had the same problem with an Edelbrock fuel pump in my BBC. The first pump I used was a Summit unit, which worked fine but when I went to change the fuel inlet fitting that part of the casting broke off. Apparently a common problem with these pumps. Next up was the Edelbrock unit. I only had it for a few weeks when it started doing the same as yours, fuel pressure dropping from about 6 PSI to about 1 PSI. Was able to return this one to Summit and purchased a Carter pump which is still working great.
     
  7. 1971BB427
    Joined: Mar 6, 2010
    Posts: 9,816

    1971BB427
    Member
    from Oregon

    I've seen this before and my thinking is tolerances changing as the engine heats up and transfers heat to the pump body. If things are marginal clearance when cold, and then change with temperature it can cause this sort of problem.
    I've seen this with some brands of pressure regulators also. Set them cold, and once they got heated from under hood temperatures the pressure drops 2-3 lbs. I try to mount my regulators down low towards the front of the frame rail so engine temps up higher wont affect them as much.
     
    Pist-n-Broke likes this.
  8. 54FISH
    Joined: Jan 10, 2011
    Posts: 421

    54FISH
    Member

    Thanks ,I'm not running a regulator , but I agree heat can change characteristics . The quick fuel carb suggest 6.5psi & for 2000 miles on build with the edelbrock ( never above 5psi) so I'm thinking get something 6-7psi & be done with it .but I'm opening it up cause I want to see what might be happening here .+ I'm done with edelbrock ,their customer service blows IMO . Thanks again!
     
  9. 54FISH
    Joined: Jan 10, 2011
    Posts: 421

    54FISH
    Member

    Thanks I got 2000 miles on pump since new build .And I don't even know if it was new , NOT sure if it was used & put back on shelf at buddies cousins shop so..... we will C .I'm curious as to what's going on here .I m gonna search for clockable 6-7 psi pump either way .thanks again brother!
     
    impala4speed likes this.
  10. pprather
    Joined: Jan 10, 2007
    Posts: 8,957

    pprather
    Member

    Carter M6900 as advised above.
     
  11. 54FISH
    Joined: Jan 10, 2011
    Posts: 421

    54FISH
    Member

    YOU WERE RIGHT! sliver of aluminum holding check valve open . Thanks !
     
  12. ClayMart
    Joined: Oct 26, 2007
    Posts: 7,793

    ClayMart
    Member

    And to a degree at least, when some employers took pride in their employees.
     
    impala4speed likes this.

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