STIHL M-TRONIC CHAINSAW HAS NO CARBURETOR ADJUST, WILL IT 'RESET' TO REGULATE FUEL CORRECTLY?

If you found this video helpful, please LIKE and SUBSCRIBE!! Today we are going to try and "reset" a Stihl MS-261C with no carburetor adjustments. It starts and runs, but is not getting enough fuel. The saw has been fully serviced and checked for all other issues and everything seems to be in working order. Unfortunately without an adjustment to give it a little more fuel on the top end, my customer will have to pay a Stihl Dealer to finish the service with their fancy dancy computer program..... Be aware! These M-Tronic devices are used on Stihl Chainsaws and brush cutters. Fortunately Echo has not put these on their outdoor power equipment.

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[eteca]

Good video. I am a Certified Stihl Technician I work for a Stihl dealership not for Stihl. The M tronic system generally works as intended. The main issue that we see with them is the solenoid that that is located on the carburetor. The valves leak and cause a rich condition where the system is no longer able to reduce the amount of fuel going to the engine. This usually causes a hard to hot restart, no idle or rough idle fault. Fine debris from the fuel gets ground up in the valve and cause them to leak.There have been several updates to the solenoid valves and the fuel filters for this issue. The m-tronic system can be checked for correct function by running the saw in the bottom "start" or triangle position. With the engine warmed up the saw should run continually in the starting position. If the engine will not continue to run in the start position then there is a fault with either the engine or the m-tronic system and further diagnostics and repairs will be required. sometimes issues get blamed on the Mtronic but in fact the engine itself has an air leak or some other issue going on. Its still more or less a standard two stroke engine. If you would like I can send you a more detailed email on how the system works. The MDG1 diagnostic tool and Stihl Diagnostics Software are publicly accessible and can be purchased through a Stihl dealer. Stihl will warranty the M-tronic system for two years under an emissions warranty that is required by law. Additionally most Stihl dealers and Stihl distributors will work with customers to get issues like this resolved even covering repairs on units that are out of warranty. This type of warranty is handled on a case by case basses often falls under the dealer and distributors discretion. Usually if you are hospitable with your dealer they will take care of you. A little kindness goes a long way. Overall Im not against the M-tronic system. It just takes a little know how to troubleshoot. Its not perfect but Stihl and all manufactures are under pressure form the governments that the sell there products in to meet ever tighter emissions standards. Just look at what has happened to the auto and heavy diesel industry its the same thing.

[TruthHurtsu]

The reset procedure depends on what version of M-tronic you have. The reset procedure you describe is for the older versions, M2.0 and below.
To check what version you have, you need to look at the CE label. In the upper right corner you should see an "M" with a number next to it, like M2.1 or M3.0, if you can't find an "M" number you probably have an older version.
On newer versions (M2.1 and over) the reset procedure is:
Put the machine in the ▲ Cold start position
Start the machine and run it in the ▲ Cold start position for at least 30 seconds but no more than 60 seconds
Do not touch the throttle or accelerate the saw during this time
Disengage/release the chain brake
Open/squeeze the throttle fully for at least 30 seconds
Engine speed varies noticeably during calibration
As soon as the engine speed drops noticeably, release the throttle back to the idle position
When the engine is back to idle speed, engage the chain brake and switch off
Everything should be calibrated.

I am a Stihl dealer if you bought the saw from me I wouldn't charge anything to adjust it. Even if you didn't buy it from me if it's just a quick adjustment I probably still wouldn't charge. Sometimes I figure a little "free" labor here and there doesn't hurt me and a little customer service and hospitality goes a long way to create loyal repeat customers. I'll end up making the money back in the long run when they return for parts, oil, bars and chains.

We tried to use our MDG-1 today and the data cable was damaged so it wouldn't connect to the saw. You can use the computer to fine tune the saw if you needed but it's not really necessary. I hardly ever use my MDG-1. The reset procedure usually does OK to get back to a standard setting. It will fine tune itself the more you use the saw.

Something else to check if it won't reset and it's just not acting right is the little solenoid on the side of the carb. If it's green replace it. They had issues with those and they've been updated. Newer solenoids are white. The black ones are good too. It's very important to use the CORRECT Stihl brand fuel filter with the M-tronic carbs. The fuel filter that should be in it is black with a white top and orange element. If it's a black filter with a white element it needs to be replaced with the correct one. Don't use the Stens or Oregon, etc.. replacement fuel filters on an M-tronic saw. The bootleg Chinese service kit fuel filter, even if it is orange, will not work either. Ask me how I know... It took a min to figure that one out because they look like a Stihl filter. However, side by side you can see and feel the difference in quality between the cheap Chinese parts the customer bought and installed and the genuine Stihl service parts.


If the engine is good, the solenoid is good, and the fuel line and fuel filter are all good and correct it may be the ignition module, even if the saw does "run". The electronics that control the solenoid are built into the ignition module.

1 year late edit: Something else to check if everything else is good (engine, solenoid, fuel line, fuel filter) You might replace the wire harness before trying to replace the ignition module. You could be getting a weird grounding issue.

[eyeswideopenz]

I am a stihl fan, I have on hand today 5 saws that I have owned and run for years including a 241 that is m tronic
I have had zero issues

[ernestodavino]

To reset the MTron properly you have to let it idle at 35 seconds then full throttle for 35 seconds You will hear the saw engage it will upper and lower its throttle on its own during the sequence there's a lot of misconception .when used properly the saws are very efficient. I'm constantly changing altitudes so I have to constantly retune my saws this feature makes this splendid

[jdmiller]

You can all thank the EPA for electronic "no tamper" carbs.
We run over 30 saws with 3 MTronic is working properly, it is awesome.
BUT, it can never be better than a fine tuned saw by an operator who knows what he is doing. We have had several MTronic saws fail in the last few years. Solenoid on the carb is the usual culprit and occasionally a bad we've converted a few back from MTronic to old type by retrofitting the Carb, Coil, and flywheel from the non MTronic version. I've done several MS201Ts and MS261C-M and a MS462 Also most of you don't realize that there are a few models that are sold to 3rd world countries without MTronic but with MTronic when shipped to north america.

Personally I think of these new versions as Moronic you are out on a job and hours from a dealer and your saws decides to stop idling or dropping rpm when full throttle.
Turn around and head to back to town? No, out the backup saw, usually and old MAC10-10 or Husky 372 and keep on the $1200 new saw sits their looking all shiny and

So just remember to thank the EPA for not regulating something that makes sense.
(like aircraft, ground 1 plane and you, and thousands of others, can run your old saw for a lifetime and more)....make the average joe suffer. Thats what governments do best.

[generatorjohn]

I own a "homeowner" Stihl chainsaw that I purchased in 2017. It was on sale, less than $200. So far hasn't given me any trouble. Seems to me if it did, be cheaper to buy another one if I couldn't get it back running on my own.
I really like your channel. So much useful information that's real handy for most folks. Thank You

[alessandromonizza]

Just a couple things to say.
First of all, u would want to put at least some cutting time on your brand new spark plug before judging the tuning by its colour, this is gonna give you the most realistic response. By only running the saw on fast idle (i'll talk about that later) and at WOT it will eventually give u the same result, but then saw would need more time running to give you a realistic outcome on the spark plug's colour than making a couple cuts in the wood.
The other thing is something i noticed in the reset procedure itself: the cold start procedure was right, and the reset procedure for that mtronic version i guess. Here's the deal: when put on fast idle, the chain actually IS supposed to run, even a lil bit, because the saw is set on a "fast" idle; that's why u're supposed to disengage the chain brake. Depending on which brand and model of saw u have, the fast idle could be set at higher or lower rpm, and this is gonna affect how fast the chain spins when on fast idle mode. On this 261 it seems that the fast idle is set relatively low, so the chain is not spinning that much. In this case, I would say that the reset procedure actually DID work, becaude after 90 seconds the chain was spinning a lot slower, ergo the engine was running less rpm at the same throttle opening, ergo the carburetor adjusted himself a bit richier. Will it be enough to make the saw run correctly? I don't know, but keep in mind that all of those electronic tuning systems will always tend to lean up a bit ur tuning, this will make the saw respect the EPA emission rules. Basically, less fuel burning and more clean air means less exhaust gases being sent out in the atmosphere. This could also mean that ur mtronic or autotune saw will always be a screaming beast, but eventually it could last less years. That is the controversial point on these systems, and u kinda exposed it in the video, really good job.
Last but not least i saw a thing (and i could be wrong, in that case u'd wanna tell me): you switched the saw from fast idle to normal idle by simply pulling up the switch, and it looked like u were struggling pullin it. It is because that switch is NOT supposed to be pulled up to get into normal running position, the only way to pull it up is revving the saw up (as u did later); by doing it u will disengage the fast idle position, that is held down by the throttle lever itself, and the switch (which has a spring in it) will come up to normal running position by itself. Doing it the way it seems u did may break the fast idle mechanism, which is obviously not good.

[stevie]

I bought a stihl ms201t-m several years ago. A piece of junk it’s been long gone. Echo CS355t controls are very similar and it starts and runs. Thanks for a great YouTube channel.

[filfarmerpacnw]

I bought a 261 NON "C" because of this video. I have already adjusted my carb and its running great. Just a tip, my saw starts in 3 pulls every time. Two pulls with choke on, 1 pull on high idle and it starts.

[shannonyoung]

I've been running a MS441R C-M for more than 5 years, and it is easily the best chainsaw I've used in my 40+ years of sawing. Starts easier than any saw I've ever used, is always in tune, and has a very flexible powerband. Mine has been ported (cylinder was milled to allow port timing adjustment) and has the squish tightened. I run non-ethanol high octane fuel to maximize the output, and my 441 will absolutely spank a stock 660. Count me as a M-Tronic fan, big time.

[tlpoutdoorsman]

I have a carb ms 270c bought new in 85, run it all winter long, have changed the spark plug once, and the fuel filter once. Have done nothing else. Have never had 1 problem. Im absolutely amazed!!

[coreygraham]

I got the ms 261 stihl with out the computer junk and never once had a issue. When I do fire fighting I use a husky with the computer and it’s almost impossible to restart after it being warmed up. I’m sticking with the old school carb I can adjust myself! Nice video

[beingthere]

I have one M-Tronic saw, an MS201TC that I rebuilt from a junk saw that looked like it had been dropped out of a tree. The innards were fine, and after some reconstructive "plastic" surgery, it was ready to run again. Generally it is easy to start and runs great, but I've noticed that when pushed beyond its intended use as an arborist's saw (when you need to buck some large oak branches and it's the only saw you have at that location), it will cut off at idle after about 30 minutes and will not restart until it cools off. I was suspecting the coil or the M-Tronic system, but after reading some of the comments, I'm going to take a good look at the solenoid.

As for the plug condition reading, the real interest is what's going on at cutting speed at WOT under a cutting load. It would seem to me that a better test would be to buck a log of diameter appropriate for bar length at a normal work pace for about ten minutes, and after the last cut let it idle 30 seconds, then cut it off and pull the plug. Most of the time would have been spent in actual cutting, thereby reflecting the spark plug appearance that would be most accurate and useful.

[hickorystx]

Great advice, and explaining the down side of the m-tronic stihl feature. I do appreciate your honesty.

[richardbuchli]

I have a Stihl 028 Wood Boss that I bought from a old gentleman back in 1990. He told me that he bought it new in 1979. He told me when I bought it that it had an air leak between the casing and sold it to me for $75. I took it to a Stihl repair shop and had it fixed for $50. This thing still runs great. That shop and two others told me that I could go over to the display shelf, pick out any Stihl chainsaw I wanted and they would swap me even. I was hesitant and just said no thanks. After the third guy told me that I asked him why was he willing to do that. He told me that Stihl no longer made their casings out of metal and they now made them out of some type of plastic and they had changed the ignition over to an electronic system and it just wasn't as dependable. Glad I didn't fall for an unblemished new chainsaw. Mine looks rough but it is a workhorse and it has never let me down.

[sm]

I've been a STIHL dealer for 19 years. The only way to correct the problem is to replace the (H) speed solenoid, that is if the inlet screen is clean and the upper diaphragm is soft. That'll set someone back about $90 bucks, parts and labor, in my shop. The solenoid changes out fairly easy, but after doing that you have to do what's called a "Learn Idle".

1. Start and idle 90 seconds in the start position then blip the throttle and shut off immediately.
2. Start and idle in the run position 60 seconds.

FYI, the only M-Tronix saws that I sell are the M-Tronix only saws. The MS261 comes both ways as do a number of other saws....

[wim]

Your channel is absolutely amazing. The comments on here are a goldmine! Thank you!

[TommyJH]

All I own for my home is Echo! Always starts, always works, always easy to get parts!

[gregmaxfield]

Hmmmm i think i will stay with my old "adjustable" carbs in my 2 saws, easy to service myself or at my local shop. Love your work ! 🚜😊

[Leonardokite]

I have that same saw and I love it! I've found that after running it hard NOT to just turn it off, but let it idle for 15-20 seconds and then there is no problem starting it back up.