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adjusting pump pressure??????

Discussion in 'Fisher Engineering Discussion' started by sparksrides, Dec 3, 2008.

  1. sparksrides

    sparksrides Senior Member
    Messages: 154

    i was wondering how to adjust the pump pressure on a mm1 sehp pump. the mechanic's guide say's in the pump pressure test section: pump pressure is OK at 1450-1850 psi. if the pressure is low,remove pump,clean or replace filter and adjust pressure. turn adjusting screw clockwise to increase pressure(1/4 turn equals approximately 225 psi: i cleaned the filter but don't know where the adjusting screw is. side to side is fine but when i lift the blade it just seems slow
     
  2. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    The pump press relief screw is right on the side of the gear pump itself. If its the older die-cast pump it will be right beside the inlet filter. If its the later all steel pump it will be on the opposite side of the inlet filter.

    Just a note...be sure you have a pressure gage to actually check your settings before you touch it. You can do more harm than good by changing the press setting by using the "shot in the dark" method.
     
  3. sparksrides

    sparksrides Senior Member
    Messages: 154

    thank you kindly sir, i guess i'll gage it first. any other reason it would be slow to rise and not side to side
     
  4. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Lots of other things besides low pump press can cause a weak lift. Worn motor, weak battery, undersized cables, or a poor connection.
     
  5. sparksrides

    sparksrides Senior Member
    Messages: 154

    yah i think part of the problem might be the power plug at the quick disconnect it looks a tiny bit melted, just replaced both batteries last month, solid heavy gage power wire on both sides of the harness. the lights do dim hard, especially when lifting but then again every plow i ever ran dimmed the lights. i'll have to see what kinda amp's the motor is pulling and look into replacing the power harness even if it's not 100% the problem, it will probably get worse as the season goes on. where can i get a gage and what range should it be? by the way i relay appreciate the help,as this is my first fisher.
     
  6. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Grainger has inexpensive pressure gages. Found them as cheap as $25 there.

    Set it to 1800 psi on the money. If it isn't capable of developing it then one of the issues I previously described is likely the cause...including your melted cable connection, so be sure to go over those.