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New MS-261CM hard starting when hot

Started by sumpnz, April 18, 2021, 08:17:11 PM

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sumpnz

Got my new MS -261cm finally.  First use it was definitely putting a big smile on my face.  However, today, while it started just fine first time it fired it up, any time I shut it down it was really hard to restart.  It would sort of run but would die if I let do it's thing, or would burble, bog and die if I gave even a little throttle.  If I could get it to run, which might take 15+ attempts (not just pulls, 1 attempt might be 1-5 pulls) it runs great.  It's a great saw when it's running.  But I'll get sour on it quick if hot restarts don't improve.

Jim Chance

Did you happen to return it, because I bought a MS261CM demo that does the exact same thing! Mine appeared to be vapor locking - different fuel seems to have mostly fixed that. It also seems to flood if I crank it in "start" when hot. Cranking in "run" with WOT seems to work when it does not start (and isn't vapor locked). I am going to do the recalibration procedure and see if that helps.

sumpnz

I'm using the same gas that runs GREAT in my 461, and the log splitter and riding mower, as well as the FS-250 and a smaller Stihl string trimmer.  It's non-ethanol 89-octane gas.  Pretty fresh.  Mixed about 40:1.

Jim Chance

Supposedly that is what my gas was too, but mine gave me trouble in two different saws, both M. Have not tried it in anything else. I am pretty sure it was a bad batch and vapor locking. On my MS201c the pump bulb went dry, it wanted to geyser, and when I looked in the fuel tank bubbles were coming out of the fuel filter. Have you tried resetting the mtronic? There are three different methods. It is hard to figure out which one to use. The other thing I hear from rumor control is that Ms misbehave if run dry. Since running dry is basically killing the saw by leaning it out, maybe the mtronics goes to full rich and floods it? When mine is being balky I start it in "run" with WOT. If it is not vapor locked, that seems to work


Tacotodd

Have you tried to just let it idle for a bit, like 45 seconds before you shut it down? That might help, might not. Would be worth a shot. That will allow it to acclimate itself to the ambient temps well. Always allows it to restart well when cutting with it frequently. Can't hurt to try, and basically cost nothing.
Trying harder everyday.

axeman2021

Is your Stihl dealer one who has the software Sthil has to run on a laptop computer to check the Itronic CMs?

kantuckid

My Stihl MS-241 is also motronic (wires to carb, no adjustment screws, etc.) and does that lately same as OP. My dealer is a top trained Stihl guy/dealer with the right stuff to repair my saw, but also a mom & pop store that sells lawnmowers too. They cannot work on my saw yet after a month due to mower sales from $JB guvment bucks$ . I don't blame him but could use the saw too-if my tractor wasn't also dead. ;D
Cold mine started normally and ran great until hot then wouldn't idle well and stopped and after a hard hot re-start it balked badly. Low hours saw run on 89 gas. 
Kan=Kansas;tuck=Kentucky;kid=what I'm not

axeman2021

With my CM261C-M following the Stihl Manual instructions to calibrate the saw, set on full choke after it starts leave it on full choke for around a minuet, then power on full as the chains speed makes changes going faster saw is now calibrated.

This took care of the saw shaking i had after starting, and made the saws chain move much faster.

kantuckid

There are zero such calibration instructions in the owners manual for my MS241C saw. There is a short concise sentence that says it has no adjustment screws as the M=tronic makes them not necessary... :D 
Were it not for my tractor clutch going kaput I'd have already bought another saw as my Stihl 170 is not enough saw for trees waiting on me, plus it needs to have some life left for my cabin wall logs. 
Kan=Kansas;tuck=Kentucky;kid=what I'm not

doc henderson

I have posted elsewhere, but my 261 did this, solenoid tested fine,  not fixed until they replace the M-tronic.  now runs great.  acted flooded when warm.  get them to fix it under warranty.  the dealer should know this is a problem.  my tech said it was fine, finally the owner told him to just replace it on third trip to dealer.  I think they just used an ohm meter for the test.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

sumpnz

Seems letting my saw idle for 30-45 seconds before shutting down is the trick.  Did several hot starts over the weekend, and so long as I gave it that idle time it would fire back up just fine.

kantuckid

The fact that my M-tronic saw ceased to idle was one reason I took it to the dealer. 
Kan=Kansas;tuck=Kentucky;kid=what I'm not

axeman2021

This is where i reached out to Stihl Tech. support, asking them if i alwasys  needed to recalibrate my CM261C-M everyting i started it.
After i calibrated my CM261C-M after it having a rough idle each time it was started, the idle was fine and then each time i restarted it the idle was smooth with no roughness.
There answer below.
===========

Thanks for taking the time to reach out to us. The calibration procedure only needs to be followed following periods of erratic idling. I have M-Tronic units that are 5+ years old that I have never calibrated.

Kind Regards,

Joseph
Technical Services
STIHL - Virginia Beach, VA

kantuckid

I was in RK last week and the saw guy there said he'd sold over 50 non-motronic 261's during covid. @ $620 a pop that's a bunch of saw money. Not a saw price point you'd think would move like that? 
 Only sold one motronic 261 in the same time span as he said the customers told him the word on the web had steered them away from non-adjustable carb saws. They get LOTS! of ebay bids too. Even older 260's sell same way-lots of bids and used for over original prices. 
Kan=Kansas;tuck=Kentucky;kid=what I'm not

axeman2021

If I remember people were saying about the same things ,when fuel injection started replacing carburetors on cars.

kantuckid

As it stands with my M-tronic saw I'd certainly go for some carb screws. Both carb with screws and fuel injection I can work on OK. M-tronic requires a Stihl dealer. My dealer has bad feet, a one man show with his wife and had it for over 6 weeks now. After I heard his multiple foot doc visits story (I really empathize with the working man who has health issues! as there's no free lunches for them) added to his overwhelming mower sales from JB bucks throw in my tractors clutch went out and I decided to stick with him. 

But the old FI stories are true as are the computerized engines stories.  My OBD device doesn't work on my chainsaw. :D 
Kan=Kansas;tuck=Kentucky;kid=what I'm not

axeman2021

Quote from: kantuckid on May 03, 2021, 07:42:28 AM
As it stands with my M-tronic saw I'd certainly go for some carb screws. Both carb with screws and fuel injection I can work on OK. M-tronic requires a Stihl dealer. My dealer has bad feet, a one man show with his wife and had it for over 6 weeks now. After I heard his multiple foot doc visits story (I really empathize with the working man who has health issues! as there's no free lunches for them) added to his overwhelming mower sales from JB bucks throw in my tractors clutch went out and I decided to stick with him.

But the old FI stories are true as are the computerized engines stories.  My OBD device doesn't work on my chainsaw. :D
Have you tried the calibration procedure i posted above?

kantuckid

Yes I did and if you'll read my previous post above-you cannot do that with a saw that doesn't want to idle to begin with? Plus it's balky. The dealer that has it is a guy in early 60's who's his own main mechanic and has had all Stihl trainings offered. Pro loggers take him their saws which is telling.   
He did tell me he's found that the newer fuel filters caused problems not seen with the older filters as much finer micron effect.
 I'll report here when I've learned more.  
Kan=Kansas;tuck=Kentucky;kid=what I'm not

axeman2021

Quote from: kantuckid on May 03, 2021, 08:08:20 AM
Yes I did and if you'll read my previous post above-you cannot do that with a saw that doesn't want to idle to begin with? Plus it's balky. The dealer that has it is a guy in early 60's who's his own main mechanic and has had all Stihl trainings offered. Pro loggers take him their saws which is telling.  
He did tell me he's found that the newer fuel filters caused problems not seen with the older filters as much finer micron effect.
I'll report here when I've learned more.  
I have also read of a change in the coils from the older systems that has fixed many older CM261C-Ms.

kantuckid

On this recent ph call I asked dealer about the coil breaking down as a possible cause-he said the coil on an M-tronic saw is tied into the M-tronic system, as if it's not a simple one part diagnosis. Honestly I was ready to fetch the saw and take to another dealer but decided it made no sense as he says he's catching up on repairs now after several truckloads of mower assemblies/sales and I have my tractor dead-ended at another shop anyway.    
Kan=Kansas;tuck=Kentucky;kid=what I'm not

axeman2021

Quote from: kantuckid on May 03, 2021, 08:52:03 AM
On this recent ph call I asked dealer about the coil breaking down as a possible cause-he said the coil on an M-tronic saw is tied into the M-tronic system, as if it's not a simple one part diagnosis. Honestly I was ready to fetch the saw and take to another dealer but decided it made no sense as he says he's catching up on repairs now after several truckloads of mower assemblies/sales and I have my tractor dead-ended at another shop anyway.    
Here is a online video of replacing the M-tronic coil on the Sthil CM261C-M give it a look, and maybe you could just buy the coil and install it yourself.
Replacing The Ignition Coil On A Stihl MS 261 Chainsaw. - YouTube
vide of replacing the coil on a Stihl M-tronic CM261 C-M chainsaw - Bing video

But the main thing is getting the new fuel filter and new coil on your saw.

kantuckid

Thanks but the youtube video is for a straight 261, not an MS-261CM -> M-tronic saw.  My dealers reply was to suggest that it's throwing on parts with my saw to simply replace the coil as a stand alone part. No, I am not in the know on a chipped, non adjustable carb saw and will leave it to the dealer to diagnose.  
Kan=Kansas;tuck=Kentucky;kid=what I'm not

axeman2021

Quote from: kantuckid on May 03, 2021, 09:54:34 AM
Thanks but the youtube video is for a straight 261, not an MS-261CM -> M-tronic saw.  My dealers reply was to suggest that it's throwing on parts with my saw to simply replace the coil as a stand alone part. No, I am not in the know on a chipped, non adjustable carb saw and will leave it to the dealer to diagnose.  
Good Luck.

Tacotodd

Quote from: kantuckid on May 03, 2021, 07:42:28 AM
As it stands with my M-tronic saw I'd certainly go for some carb screws. Both carb with screws and fuel injection I can work on OK. M-tronic requires a Stihl dealer. My dealer has bad feet, a one man show with his wife and had it for over 6 weeks now. After I heard his multiple foot doc visits story (I really empathize with the working man who has health issues! as there's no free lunches for them) added to his overwhelming mower sales from JB bucks throw in my tractors clutch went out and I decided to stick with him.

But the old FI stories are true as are the computerized engines stories.  My OBD device doesn't work on my chainsaw. :D


My OBDII doesn't fit either, oh well.
Trying harder everyday.

axeman2021

Quote from: Tacotodd on May 03, 2021, 05:09:43 PM
Quote from: kantuckid on May 03, 2021, 07:42:28 AM
As it stands with my M-tronic saw I'd certainly go for some carb screws. Both carb with screws and fuel injection I can work on OK. M-tronic requires a Stihl dealer. My dealer has bad feet, a one man show with his wife and had it for over 6 weeks now. After I heard his multiple foot doc visits story (I really empathize with the working man who has health issues! as there's no free lunches for them) added to his overwhelming mower sales from JB bucks throw in my tractors clutch went out and I decided to stick with him.

But the old FI stories are true as are the computerized engines stories.  My OBD device doesn't work on my chainsaw. :D


My OBDII doesn't fit either, oh well.
As i have posted to other forum members with problems with their Stihl M-tronic saws, try running the calibration process on your Stihl  M-tronic saws.

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