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Stiihl Fs85 Problem

Discussion in 'Mechanic and Repair' started by BASIC, Jun 11, 2003.

  1. BASIC

    BASIC LawnSite Member
    Messages: 83

    Hi I have a Stihl FS85 trimmer/brushcutter,yesterday it started giving me a problem.When the throtle is fully depresed,it works fine but if you let up on the throtle it seem like its going to stall(it did once).Do you have any ideas what it may be and how to fix it?Thanks as aalways for any help you may give,BASIC.
  2. ducky1

    ducky1 LawnSite Senior Member
    Messages: 252

    sounds like it is running lean. Could be out of adjustment, if the carb has adjustments, maybe a plugged fuel filter or dirty carb. Did you happen to change grades of gas when it started doing this? If so, go back to what was working. Good Luck
  3. MWHC

    MWHC LawnSite Member
    from Wyoming
    Messages: 218

    We have to put carb kits in the stihl 85 trimmers about every other season. I don't think the carb has much you can adjust. Also make sure the carbon in the exhaust port is clean and the muffler isn't plugged.

    SAWDOC LawnSite Member
    Messages: 25

    Start with turning the idle up. If the problem consists you have some bigger problems.
  5. BASIC

    BASIC LawnSite Member
    Messages: 83

    Thanks guys,I trided it,I think I have a bigger problem.I'm going to take it to be serviced,I'll post what they find.Thankyou all for your help,BASIC.
  6. xpnd

    xpnd LawnSite Senior Member
    Messages: 378

    On the backside of the machine where the throttle cable goes through the throttle plate shaft, you will see a small screw on an arm. In addition to any adjustment you may have on the carb, this screw can be adjusted to increase the low idle speed.
  7. Gravel Rat

    Gravel Rat LawnSite Fanatic
    Messages: 9,544

    I must be lucky my FS-85 is 5 years old and the carb has never been touched and its got tons of hours on it and it starts and runs good every time.

    From new all I have ever ran in the machine is Stihl oil and premium fuel I won't use any mix oil besides Stihl and I never had a lick of troubles from any of my Stihl MS260 and 046 Mag plus.

    The FS-85 is the best machine I ever owned if I buy a new one if will be the same with the bike handles. I have tried the next model up and its too heavy you really notice the difference there would be no way to work on steep slopes with it.
  8. BASIC

    BASIC LawnSite Member
    Messages: 83

    I tried all the sugestions made,thankyou all but I'm still having problems.When it works,it does a good job but it has given problems for the three years I've owned it.The shaft is also to short(for me).Hopefully I'll find out whats wrong in about two weeks when it's back from service.I'll let you all know what they found.I think the next brushcutter I get may be a Husqvarna,BASIC.
  9. creativedan

    creativedan LawnSite Member
    from IL
    Messages: 54

    try this unscrew the exhaust pull out the exhaust filter and put the exhaust piece back in
  10. BASIC

    BASIC LawnSite Member
    Messages: 83

    I brought the FS-85 in today,the service manager looked it over and started it,he said the clutch an springs were worn and would need to be rwplaced.He dosen't think theres anything serious,I should know by the end of the week,whats wrong and how much,BASIC.

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