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MS261 New Coil, now won't idle

Discussion in 'Chainsaw' started by hookset, Feb 7, 2019.

  1. hookset

    hookset ArboristSite Lurker

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    Hey All - newb here, searched a bunch on this forum and have learned a lot - so thank you in advance of any additional advice.

    Love this used saw (MS261), used for a few years always has worked great. Few weeks ago, took it out to cut some oak on a 10 degree day (last used a week prior on ash, and worked great), started, all was good, until a minute or so later once the saw was warm....rpm's slowly decreased and quit running. Couldn't get it running again, no spark.

    Cleaned air filter, put a new fuel filter in tank, was getting gas, new spark plug, still didn't have spark. Isolated the coil by removing the kill switch wire and tried in reverse with the black wire off, still couldn't get a spark.

    Ordered a new OEM stihl coil from a dealer (ouch...$>150, 11414001331), got spark with the new coil. Gapped it with the business card, ensured it wasn't hitting anything. Fired up the saw, will start on full choke/warm running setting but I have to give it throttle and engine sounds rough (like carb issues), and as soon as I let off the throttle, saw immediately dies. I can restart on choke/warm running, but same thing happens. Seems odd to me, I wouldn't think I need to re-do the carb settings, as all of that was fine before the new coil.

    Thoughts? Did I screw something up:/ Trying to save some money and not take it into the dealer so I can learn on my own, so any advice is appreciated.
     
  2. super3

    super3 Addicted to ArboristSite

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    Were you cutting with it when it quit? B4 the coil replacement?
     
  3. hookset

    hookset ArboristSite Lurker

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    I cut a few small limb pieces with it post start, and then was walking to a different area when I could hear the rpm's declining. I tried to rev a bit, and it seemed to go up, but then ultimately when i got off throttle, it killed. Thanks for the reply.
     
  4. Ozhoo

    Ozhoo Addicted to ArboristSite

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    give this a shot

    Untitled.jpg
     
  5. super3

    super3 Addicted to ArboristSite

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    How long did it warm up first?
    You may have cold scored it at 10 deg.

    Pull the muffler and have a look.
     
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  6. hookset

    hookset ArboristSite Lurker

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    Thanks Gary - this saw doesn't have the m-tronic carb in it. It's the regular with H/L/LA settings. I'm assuming this procedure wouldn't apply then?
     
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  7. hookset

    hookset ArboristSite Lurker

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    Ok, I sure hope that didn't happen. I'll pull the muffler and look. I believe I gave the saw enough time to warm, like I do all the time, I cut a fair amount in winter in WI....but you never know I suppose. I'll check compression...any idea what it should be? 150-170?
     
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  8. hookset

    hookset ArboristSite Lurker

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    Ran a compression test, assuming I'm doing it right, and it came in at 145.
    It's a hair under 150.
     
  9. hookset

    hookset ArboristSite Lurker

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    Piston looked fine after pulling the muffler. Any other thoughts? Thanks.
     
  10. super3

    super3 Addicted to ArboristSite

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    How thick was the b card you set the coil gap with.
     
  11. hookset

    hookset ArboristSite Lurker

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    Typical thickness of a standard business card....like a heavy paper stock I'd describe it. i don't have a thickness gauge to get a measurement on that. sorry.
     
  12. hookset

    hookset ArboristSite Lurker

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    I went and gapped it further, and closer....no change in how the saw runs. Thanks.
     
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  13. pioneerguy600

    pioneerguy600 Lost in Space Staff Member

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    My first thought would be to dump out the fuel tank, start with a batch of fresh mix, don`t use any mix you were previously running. Seen a few saws this winter with funky looking fuel in their tanks when they exhibited strange running problems.
     
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  14. dmb2613

    dmb2613 ArboristSite Guru

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    Adjust the carburetor after new fuel is added
     
  15. hookset

    hookset ArboristSite Lurker

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    Ok, I can do that. This gas was full premium, no ethanol with stihl ultra oil mix, in 1 gallon container from January 2019. I ran through a half gallon of the gas with no issue in this saw (before the spark problem) and a MS230 without issues, but I can get fresh batch in case it was a fuel problem. Thanks.
     
  16. hookset

    hookset ArboristSite Lurker

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    Dumped the gas from the saw, and got fresh unleaded premium with no ethanol. and mixed with the Stihl ultra oil mix, 1 gallon container. Same result, kept it running a bit longer than I had been on choke to attempt to get into the new gas, but the saw never returned to running right, or even close to idle. Seems like a carb issue, but just doesn't make sense as I never had issues with the saw running/carb issues before I lost spark. I need the saw functional, so dropped it off at the dealer....sure hope it's something cheap. I'll try to follow-up on this thread. Thanks for the help.
     
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  17. greengoblin

    greengoblin Addicted to ArboristSite

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  18. greengoblin

    greengoblin Addicted to ArboristSite

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    Sounds like it be a a seal vacuum leak
     
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  19. pioneerguy600

    pioneerguy600 Lost in Space Staff Member

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    The carb will likely need to be opened and cleaned out thoroughly , some fuel filters disintegrate inside and the tiny bits of stuff makes its way up the fuel line into the carb, fine screen in there gets blocked.
     
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  20. drf255

    drf255 BAD CAD

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    Swap the plug again. Are u using the recommended plug?

    I know it’s not MT, but worth a shot.

    I missed if it had spark now or not.
     

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