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Fisher MM2 struggles to raise

Discussion in 'Truck & Equipment Repair' started by HomeSolutions, Feb 3, 2009.

  1. HomeSolutions

    HomeSolutions Junior Member
    from Mass
    Messages: 6

    I have a 8' fisher mm2 that raises a few inches as normal then struggles to raise any higher. I put a pressure guage inline and got a reading of 600 psi when i first tried it. Thought that was way low and had a bad pump. I took the motor off cause I thought there was a pressure adjustment screw underneath. No screw to adjust that I saw. So I cleaned up some of the black soot from the inside of the motor housing and reinstalled. Tried again and pressure went up to 1000 psi at top of stroke but still had hard time getting there. I also put a current probe on the plow side power and got a reading of 130 amps. Any idea's on motor or pump being bad. Connection problem. Not sure what to replace/repair first. New ez flow fluid at beginning of season and changed again last night thinking it was that.
     
  2. HomeSolutions

    HomeSolutions Junior Member
    from Mass
    Messages: 6

    both angle cylinders work like a champ. tried angling while on pavement for some resistance and no problem.
     
  3. no lead

    no lead PlowSite.com Addict
    Messages: 1,308

    does it have enough oil in it? put it all the way up and then angle. anything?
     
  4. no lead

    no lead PlowSite.com Addict
    Messages: 1,308

    i assume it wont go all the way up? jack it up w/ a floor jack and try to angle. if it wont you need more oil. pull the motor and pump look at the oring under the pump. all good? there should be a 7/16 stud sticking out of the top of the pump. turn it 1/2 turn and try again.
     
  5. HomeSolutions

    HomeSolutions Junior Member
    from Mass
    Messages: 6

    If hold the up lever it will get there but slow and works real hard. Fluid is full and new. All the way up and angles still work. When I pulled the motor the only thing I saw was the shaft of the pump to accept the notch in the armature of the motor.
     
  6. Crash935

    Crash935 2000 Club Member
    Messages: 2,377

    Your still about 700 PSI off from where you should be. Like No Lead said, give pressure relief a 1/2 turn and check pressure again.

    Pressure relief will be be towards the back right corner of the pump as you look at it from the front of the pump and will only stick up about a 1/2 inch .
     
    Last edited: Feb 3, 2009
  7. HomeSolutions

    HomeSolutions Junior Member
    from Mass
    Messages: 6

    Under the motor housing ? I don't recall seeing anything like that. I just checked the mechanics guide from Fisher I saved and don't see it either. Tried to copy a picture to here but not cooperating.
     
  8. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,033

    Sounds like a air bubble, or not enough fluid. I had the same symptoms...It would hesitate angeling at best, and have a weak partial raise, but when on the ground angeling was almost fine.
     
  9. Crash935

    Crash935 2000 Club Member
    Messages: 2,377

    Guess it depends on if you have a SHEP or Instaact pump. The SHEP has the lift cylinder on the pump, I.A has a serperate lift cylinder.

    Are you using the mechanics guide from fisher site?
     
    Last edited: Feb 3, 2009
  10. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,033

    a duhhhhhhh! Time for bed, I'm not thinking straight again.
     
  11. HomeSolutions

    HomeSolutions Junior Member
    from Mass
    Messages: 6

    It is an instaact. I was plowing this morning and it was struggling raising for the first hour or so then it came around and seems to be working like it should. Wish I knew what caused the problem but not complaining. Thanks for the input.
     
  12. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,033

    Now that I have sleep in me......It shouldn't' matter which pump it is, it all runs off the same system. Fluid level and or a air bubble should still apply as possible culprits.
     
  13. no lead

    no lead PlowSite.com Addict
    Messages: 1,308

    problem solved????
     
  14. HomeSolutions

    HomeSolutions Junior Member
    from Mass
    Messages: 6

    yeah, fixed itself. Starting working like it should. Thanks for the help
     
  15. LON

    LON Senior Member
    Messages: 749