Stihl KM 90r-z Combi Engine problem

Discussion in 'Mechanic and Repair' started by Lance L, Jan 11, 2017.

  1. Lance L

    Lance L LawnSite Senior Member
    Messages: 333

    I purchased this stihl combi trimmer back in late 2013, it worked well at first but it didn't even make it through the end of the season with out problems. Unfortunately I had other trimmers for my guys to use, and didn't panic about getting it back to the dealer and repaired before the warranty was out. I usually fix all my own equipment anyways since it is a hassle to take to the dealer, and generally an easy fix.

    It started initially as just being hard to restart after use(which would cause me to lean towards a coil), but this was my first 4-mix in a while, so not 100% sure and didn't just want to throw a coil at it. It eventually was hard to start from cold, and then of course wouldn't start at all. I have cleaned the carb, adjusted the valves, it has spark(not sure if the strength of the spark is good or not), checked the exhaust port, everything I could think of... I have since taken it to a mechanic friend of mine who used to work at a dealer that had gone out of business, and he has done all of the same things I had done, and still wont start. Everything has been tried except the coil, wasn't ready to spend $60 on a coil and maybe not fix the problem and not be able to return it.

    Anyone have any similar problems? I was also wondering if someone could share the part number for the coil(I don't have the trimmer in my possession at the moment if the # is on the coil itself, forgive me) so maybe I can order one online since I am not anxious to support the place I would get the coil from since they will want you to leave a chain with them for 3 weeks to sharpen it......?

    The specifics: Stihl KM 90R-Z Combi Engine
    sn 295045582
    purchased in August 2013

    Thanks in advance!
  2. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,121

    A quick GOOGLE of "Stihl KM 90 coil" returned part # 4180-400-1308.
    Easy, huh ?
  3. Lance L

    Lance L LawnSite Senior Member
    Messages: 333

    Yes, and then upon further inspection it will say it fits km90 and not km90R(not all but half, and the coils were identical), so I would prefer to find out what is from somebody with access to part diagrams

    but thanks for your assistance on how to use google, you can pat yourself on the back now.
  4. Bob MacGregor

    Bob MacGregor LawnSite Member
    Messages: 221

    KM 90 R is the model with the loop handle.
    KM 90 is the model with the bike handle.
    The loop handle model has the short shutdown wire.
    The bike handle model has a longer shutdown wire.
  5. oqueoque

    oqueoque LawnSite Gold Member
    Male, from Jersey
    Messages: 3,287

    We have these. I am not a mechanic. The only problem we had with restarting them is that they would flood sometimes, and you would need to remove the air filter to start them. This might not be the same problem you have, but as I said, I am not a mechanic.
  6. Bob MacGregor

    Bob MacGregor LawnSite Member
    Messages: 221

    The KM air filters do get fuel soaked as do the two stroke models.
    You guys are aware of the muffler screens and the problems that they cause? My KM 90 manual recommends a 139 hour decarb, not sure what the newer models recommend.
    As for the comments to BigFish, he has been here for a long time and has contributed a lot to the folks that frequent this forum. Enough said! Did I get my point across to you?
  7. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,121

    Hey, much appreciated.
    You do yer share of help with concise and spot on replies also. Thanks.
    As do many others.

    Some others...not so much.
  8. Lance L

    Lance L LawnSite Senior Member
    Messages: 333

    Thanks for the clarification, and help.

    Thanks, but ya, this is not the issue, it is common practice for me to remove the air filter first whenever having an issue starting equipment.

    Muffler screens are removed before equipment even makes it on a truck, this trimmer has not made it to 139 hours, I believe it is a lemon tbh, but have heard that some models did have coil issues from the start.

    Right and I am also his senior to this site by 6 years. So your comment is null as far as I am concerned as he contributed nothing here, I do not have patience for people who are naive enough to think someone does not know how to use google in 2017... But at the same time, I guess I could have clarified that I had already found the part number via a google search, and wanted confirmation from someone that it was the correct #, but wasn't expecting someone to pull from my original post that I came here only for a part number and I don't know how to use google.

    But I have received some extremely helpful replies via Private Message, so thank you to everyone who has helped!
  9. Bob MacGregor

    Bob MacGregor LawnSite Member
    Messages: 221

    I have been "nulled"!!!!
  10. rogerdodger

    rogerdodger LawnSite Member
    Messages: 147

    LOL. way to go guys. I needed a little jest tonight. but did you get your problem solved and what was the fix?

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