Stihl trimmer problem

Discussion in 'Mechanic and Repair' started by Rougher83, Jul 26, 2006.

  1. Rougher83

    Rougher83 LawnSite Member
    Messages: 34

    Problem-After using trimmer for approx. 20 to 30 minutes it dies and will not restart. Let it set for a while and cool down, then restarts fine but will only run for another 20 to 30 minutes. Had taken to dealer for repair, and their diagnosis was carbon build up in the muffler which they cleaned along with carb. Picked it up to use yesterday and the same problem is occurring. Any help or insight would be greatly appreciated, so that I might help stear them in the right direction when I take it back. Thanks.
  2. K c m

    K c m LawnSite Bronze Member
    Messages: 1,336

    had the same problem a week or so ago. changed the spk plug and nothing. cut the wire and about 1/4inch and redid it. same thing. Take the whole unit off the fly wheel (spark plug unit) and replace it. Cost me 37+tax. This is your problem.
  3. Poncho25

    Poncho25 LawnSite Senior Member
    Messages: 369

    I have found that some of the Stihl line of products run alot better and less overheating of the eng, if you use Premium Gas in the mix instead of Regular. I have tested this on 2 of my pieces, and the one with Reg def runs rough after about 15 min of continuous use, where as the one with Prem mix, ran great...yes its more expensive but if it saves me trips to the shop and saves my equiptment I will do it for now....not sure if this is 100% true for what your talking about here, but just what I have found out.
  4. lawnmaniac883

    lawnmaniac883 LawnSite Silver Member
    Messages: 2,613

    Your ignition coil is bad. If this is IIRC a 2002 or later model year then it is under lifetime warranty and stihl will replace for free. If they dont warranty it then replace yourself.

    Remove orange shroud from top of engine.
    Locate the spark plug lead and follow back to ignition coil which will be just above the flywheel.
    Unbolt and remove the ignition coil, if you have new one then skip this step.
    Take ignition coil to dealer and get a replacement, usually easier since you will have the P/N from the old one.
    Install new ignition coil by first rotating flywheel until the magnets are on top then place new ignition coil in its place and thread in the screws until snug then back off 1/8th a turn. Take a business card and insert between the flywheel and ignition coil pickup to set the airgap, tighten down screw(do this on each side)
    Reinstall orange cover, connect spark plug lead and voila! Start the trimmer and you are back in business.
  5. lawnboy dan

    lawnboy dan LawnSite Gold Member
    Messages: 3,716

    this exrtemly common problem is why i gave up sthil equiptment. there is no excuse for this and they should have a lifetime warrenty on the coils but dont!
  6. TheLawnBarber

    TheLawnBarber LawnSite Senior Member
    Messages: 539

    what model is it?
  7. cush

    cush LawnSite Senior Member
    Messages: 352

    I agree bad coil
  8. Jim@MilkyWay

    Jim@MilkyWay LawnSite Senior Member
    Messages: 472

    After you tighten screws, then REMOVE business card.:laugh: :laugh:
  9. lawnmaniac883

    lawnmaniac883 LawnSite Silver Member
    Messages: 2,613

    :laugh: :laugh: :laugh: ya got me there. Guess some paper mache wouldnt be good for a small engine eh?
  10. Roger

    Roger LawnSite Fanatic
    Messages: 5,943

    Using a feeler guage (not a business card), what is the gap? It must be 0.010 or 0.012, right?

    I replaced my coil earlier this season (FS85 trimmer), and set the gap about 0.010. The motor seems to start and run fine, but am I out of spec?

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