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stihl trimmer trouble

Discussion in 'Mechanic and Repair' started by bamacutter, May 8, 2007.

  1. bamacutter

    bamacutter LawnSite Member
    Posts: 21

    ive got a trimmer that runs great for about 15 mins then shuts off. i have to wait 5-10 mins before it will start again and then it shuts off after other 15 mins of use. Anyone got any suggestions on what is causing this?
  2. Stinchcomb Lawn

    Stinchcomb Lawn LawnSite Member
    Posts: 95

    The problem is it's a stihl. Stihl on the truck because it stihl won't start. Get something that will start so you can use it !! been there I know how it feels.
  3. topsites

    topsites LawnSite Fanatic
    Posts: 21,653

    Replace air filter and spark plug, clean out any debris in muffler, perhaps replace if dirty inline fuel filter, do a compression test. If all that checks out, look for fuel leaks and bad connections / loose wires, then clean out carb real good with some carb cleaner, next I would suspect the ignition coil but you'll need a spark tester.

    It could be any of that, but if it runs until hot then it might be the coil... I'd check that choke valve also, you're not per chance leaving the choke on are you? Seriously thou, check make sure it opens.
  4. Runner

    Runner LawnSite Fanatic
    Posts: 13,496

    I'll bet you a dollar to a donut that it is your gas cap. It is not venting properly and causing a vacuum. When it does this, loosen it, put it back on, and give it a few pulls. It will fire right back up. They put the wrong types on these all the time.
  5. Roger

    Roger LawnSite Fanatic
    Posts: 5,920

    It could be the ignition module is failing. It is getting hot, then failing to work properly. The cool-down will allow it to resume working, then it fails again when getting hot.

    The above ideas are also good places to start looking for the problem.
  6. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,190

    You can usually nail a bad coil problem by measuring the resistance cold and then when it fails immediately measure the resistance again...obviously an open won't give spark....this is sure fire but usually works.
  7. Andyshine77

    Andyshine77 LawnSite Member
    Posts: 147

    1. It could be running lean and over heating. If this has happened the top end could be gone.

    2. Check compression, the top end could be bad, when it heats up you start losing compression.

    3. Bad coil. When it gets hot it cuts out.
  8. Jay74

    Jay74 LawnSite Member
    Posts: 57

    Stihl has a problem that can be traced straight to their Zama carb. A Stihl with a Walbro is a whole different machine - it will actually start!

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