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  1. #1
    Bronze Member
    Join Date
    Feb 2010
    High Rolls NM
    MF 50H LBH

    Default Adjusting fuel mixture Lucas Cav injector pump

    After a phone consultation with DieselTech I had a go at "derating the fuel" on my MF50 backhoe. Continued from this thread

    Took the little plate off the side of the pump and found this

    The notch in the middle is what moves after you loosen 2 12 point 5/16 bolts. Turn the engine over until you can get to the one on the away side, then back to the one that is near the notch. Loosen both bolts a turn or 2.

    Then to adjust fuel move that little notch. In the direction of rotation to lean, away from rotation to richen. Full lean looks like this, the notch is at the bottom of the picture now.

    I moved it to full lean and put it back together. By the way, you need a good quality 12 point 5/16 wrench as those bolts are TIGHT.

    I couldn't get it to start. Bled it & bled it and no joy. So, took it back apart and moved the adjustment back half way to where it had been. More bleeding & more bleeding and finally fired up. It seems better but haven't really tried it on a steep hill to see what I have.

    I think I just hadn't bled it enough the first time, readjusting it probably wasn't necessary.

    So, that's all I know for now other than the info I found on the web was not correct.

    Joe H

  2. #2
    Veteran Member banjodunn's Avatar
    Join Date
    Jun 2008
    Ararat Vic Aus

    Default Re: Adjusting fuel mixture Lucas Cav injector pump

    G'day has it fixed your excessive smoke prob Joe?


  3. #3
    New Member
    Join Date
    Sep 2017
    david brown 950

    Default Re: Adjusting fuel mixture Lucas Cav injector pump

    hello, joe h

    your last picture for my identical pump would be the "FULL FUEL" position. i tried putting the notch at the top and that gave me almost no power and took a while to start. (make sure both bleed screws are open, then close the bottom one when bubbles r gone, and loosen two injector fittings for guaranteed success). i gave it a go only to find it had almost no power and no soot. ripped it apart and put the notch on the bottom and she fired up with two injectors loose. (GLOVED HAND WAS READY TO SQUASH INTAKE!!!!) TONS of power!! ITS as they say ... ROLLIN COAL. Going to shut her down and turn that notch up a 3rd to lean it out a bit. dont want to crush a rod cause she is not for pullin.

  4. #4
    Platinum Member
    Join Date
    Apr 2010
    South Carolina

    Default Re: Adjusting fuel mixture Lucas Cav injector pump

    The thing about those pumps is> if you can see the plate MOVE.. you went to far..
    Good luck..
    IF the pump was set correctly at one time, for the correct application..[pump AND INJECTORS matched to engine] & your rolling smoke.. more than likely its not a pump problem..
    I don't know the story behind your decision to dive into the pump..??

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