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mCculloch FR2.0

Discussion in 'Mechanic and Repair' started by Buckshot06, Apr 15, 2007.

  1. Buckshot06

    Buckshot06 LawnSite Member
    from MI
    Messages: 3

    I inherited a Mac chainsaw. FR2.0 - it runs, wide open. If you let off the gas at all it dies. I took the carb out of it, didn't find any major debris or anything questionable. I put it all back together brought the H and L needles about 4 turns out. I got it goin and adjusted the high till it sounded like it was doin okay. The low needle wont change the saws performance, even with it closed all the way up.

    What do you guys think? Weak pump/diaphram?

    Fuel filter is new - plug is good.

    Thanks in advance.

  2. Buckshot06

    Buckshot06 LawnSite Member
    from MI
    Messages: 3

    No ideas anyone?
  3. bob91343

    bob91343 LawnSite Member
    Messages: 1

    Did you ever get that chain saw working? I have one and the little rubber bulb you press to prime it has torn away. How do I get another, or fix this?

    Not very good with tiny gasoline engines.
  4. echoman8

    echoman8 LawnSite Senior Member
    Messages: 293


    About the bulb?

    Below is a copy of a post a few days ago.


    I have had problems with the "so called" primer bulb on echos and other small 2 cycle engines.

    The bulb does not prime the carb, it just loads it with fuel if it is empty. To do this, it has 2 rubber valves (duckbill valves). With age they quit working.

    I remove the bulb, cut a piece of plastic (freezer bag), place between the bulb and carburetor housing, then put the bulb (and metal plate) on.

    This disables the primer(actually purge pump) and you will have to depend on the choke to start (cold start only) just like it was in 1990 and before.

    The duckbill valves allow air to enter the carb irratically (when bad).

  5. echoman8

    echoman8 LawnSite Senior Member
    Messages: 293

    You may have had great success with Macs, but some of us old mechs take a time out when it comes to them.
  6. Phil G

    Phil G LawnSite Senior Member
    Messages: 844

    I thought I was the only one who did that :drinkup:
    atb Phil

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