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  • Fuel Systems

    Ok, todays challenge is finishing my new fuel system.

    I have two Mallory 140's pushing fuel forward via a single -8 braided line to a dead-head regulator up front. I know, I really need a -10 main feed with a return-style regulator for this sort of volume. That will come in the next build cycle.

    I just finished rebuilding the fuel pumps and have them on the bench, trying to (re)set the pressure relief on each. As you would expect, it's a simple setscrew/locknut combo. I'm testing one pump at a time, using a 15 lb pressure gauge on the the output side. I fire the pump up, bleed any air out, and then check the pressure out. I kill the pump, tweak the set screw and repeat.

    My problem is I can't seem to get the dead-head pressure to change, it just keeps pegging my 15 lb gauge. I would expect that I could set the highside standing pressure to whatever I deem appropriate, merely by adjusting the set screw / spring pressure.

    For those of you in the know, what should my dead-head pressure be for these pumps ? For obvious reasons I don't want to run it any higher than is neccessary. I should also add that I *think* these are 140's and not 110's, tho I have nothing on the pumps to indicate. The 110 & 140 pumps use the same rebuild kit, so I'm not sure it matters for what I'm addressing here.

    At times I can be dumb as a bag of hammers, but I don't see anything obvious I'm missing here. Any suggestions ?

    Is this an 'operator error' situation? Are you supposed to manually adjust the max pressure on these pumps or do you peg the set screw all the way down and drive on ?

  • #2
    Re: Fuel Systems

    Some of the pumps I used at work for dyno fuel systems could not be deadheaded. They would just peg the gage, so you had to build a bypass pressure relief system. You adjust the supply pressure by controlling the bypass flow rate. Don't know if your pumps fall into this category, but they might.

    Just a thought
    Dan

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    • #3
      Re: Fuel Systems

      I would set them up using the same pressure regulator gauge you plan on when you install them. That way there is some flow -- if you set up your regulator to 6 or 7 psi (as running) then maybe you can set you pumps at 15-16 psi.

      Comment


      • #4
        Re: Fuel Systems

        I don't know the pumps, but maybe 15psi is the lowest pressure they put out. Try a higher pressure gauge and see what you get.
        Cognizant Dissident

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        • #5
          Re: Fuel Systems

          I once bought an ATL fuel cell with a built in pump , they sent me the one for EFI , and I had webers , sure did overpower the old timey regulator

          Comment


          • #6
            Re: Fuel Systems

            I have the Mallory 250 with a built in bypass and it came set on 18 psi. I backed it up to 15 psi by deadheading at the regulator.

            Comment


            • #7
              Re: Fuel Systems

              Originally posted by wikd69
              Ok, todays challenge is finishing my new fuel system.

              I have two Mallory 140's pushing fuel forward via a single -8 braided line to a dead-head regulator up front. I know, I really need a -10 main feed with a return-style regulator for this sort of volume. That will come in the next build cycle.

              I just finished rebuilding the fuel pumps and have them on the bench, trying to (re)set the pressure relief on each. As you would expect, it's a simple setscrew/locknut combo. I'm testing one pump at a time, using a 15 lb pressure gauge on the the output side. I fire the pump up, bleed any air out, and then check the pressure out. I kill the pump, tweak the set screw and repeat.

              My problem is I can't seem to get the dead-head pressure to change, it just keeps pegging my 15 lb gauge. I would expect that I could set the highside standing pressure to whatever I deem appropriate, merely by adjusting the set screw / spring pressure.

              For those of you in the know, what should my dead-head pressure be for these pumps ? For obvious reasons I don't want to run it any higher than is neccessary. I should also add that I *think* these are 140's and not 110's, tho I have nothing on the pumps to indicate. The 110 & 140 pumps use the same rebuild kit, so I'm not sure it matters for what I'm addressing here.

              At times I can be dumb as a bag of hammers, but I don't see anything obvious I'm missing here. Any suggestions ?

              Is this an 'operator error' situation? Are you supposed to manually adjust the max pressure on these pumps or do you peg the set screw all the way down and drive on ?
              All I can say I had the same pumps and was told by many others not to use MALLORY pumps and they were right I was doing the same thing you were I went to Holley Black pumps 140 they work great.

              Comment


              • #8
                Re: Fuel Systems

                Originally posted by bbnova
                All I can say I had the same pumps and was told by many others not to use MALLORY pumps and they were right I was doing the same thing you were I went to Holley Black pumps 140 they work great.
                Thanks for the response.

                What problem did you run into with the Mallorys ? It would cost between $350 and $400 to change these Mallorys out and I'm trying to avoid that. I will eventually go to a full return-style regulator and these pumps won't be pushing against a dead-head all the time. When that happens a lot of the issues I have with pressure regulation out of these pumps will go away.

                Comment


                • #9
                  Re: Fuel Systems

                  Finally got everything installed last nite. I still have one braided line to shorten up and some carpet issues to deal with, but I'm pretty much done with this build cycle. Now we go back to cruising aimlessly around the valley again.

                  YIPPEE !!! ;D




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                  • #10
                    Re: Fuel Systems

                    The problem I had was with the pumps and regulators, first regulators would not hold pressure no matter what I did to set then and yes I had
                    a return line.The pumps would burn out and trying to set pressure at the pumps would not work. I put on two holley blacks and the small regulators,they feed a 540 and plate and fogger system. They have been on for 3 year with a problem.

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