aftermarket ignition coil MS261 M-tronic?

[SCHallenger]

I read the thread before I posted.

Mtronic coils prefer a smaller air gap and need to be turned over faster than older coils require to make good spark.

I’ve never replaced an Mtronic coil, but I’ve replaced dozens of fuel solenoids. Particularly in the 261cm. Which is why I suggested that.

Why not just replace the plug first? I remember my "very young" & recently ported 241 suddenly deciding to not start. I took a flier & replaced the plug, & bingo, problem solved. Also, it's a good idea to make sure you have a fair amount of fuel in the tank!! Ask me how I know!! LOL!!

 

[huskihl]

Why not just replace the plug first? I remember my "very young" & recently ported 241 suddenly deciding to not start. I took a flier & replaced the plug, & bingo, problem solved. Also, it's a good idea to make sure you have a fair amount of fuel in the tank!! Ask me how I know!! LOL!!

Hi Stayner.
Yep, always want to start small

 

[SAWMIKAZE]

You are right. Fixed two 261CMs by replacing fuel solenoids. All I had were new Green solenoids. What is your opinion on the Green solenoids?

They work fine, I've put them in 3 261s so far and they cured the erratic running problems.

I did one about 2 weeks ago and they guy says it's problems are gone and runs like a top.

 

[ATH]

The saw had been running OK, so I kept at it. It quit again and won't fire. I get no spark - even trying with the drill.

Here are some pics...not sure what all you needed to help @MartDalb but here is a start. Let me know if something else would be useful.

(Plug is new...tried another plug too)

Thanks for any thoughts anybody can offer!

 

[SteveSr]

The saw had been running OK, so I kept at it. It quit again and won't fire. I get no spark - even trying with the drill.

Here are some pics...not sure what all you needed to help @MartDalb but here is a start. Let me know if something else would be useful.

(Plug is new...tried another plug too)

Thanks for any thoughts anybody can offer!

View attachment 1010405View attachment 1010406View attachment 1010407View attachment 1010408View attachment 1010409

Don't forget the wiring harness!!! Connections can become intermittent due to contamination with crud or poor crimp connections at the manufacturer.

If the ignition module can't sense the correct solenoid resistance or kill switch it will likely disable the spark.

Sure wish I could find some theory of operation info for the M-tronic system. The above is based on a 30 year career in embedded electronics.

 

[Lightning Performance]

Don't forget the wiring harness!!! Connections can become intermittent due to contamination with crud or poor crimp connections at the manufacturer.

If the ignition module can't sense the correct solenoid resistance or kill switch it will likely disable the spark.

Sure wish I could find some theory of operation info for the M-tronic system. The above is based on a 30 year career in embedded electronics.

It's a pretty simple system. They use the high circuit to tune the motor just a bit leaner than a carb at all RPMs. If that one part fails to float around just right you got issues like my Mtron 362V1. Squeeze the trigger ever so slightly and it surges like a funny car does. It does nothing else wrong so I'm not touching it. Many others have way more problems with hard starts. This saw has none of that. I did open the muffler exit some and it changed nothing. Just a weird quirk in this one.

 

[MartDalb]

The saw had been running OK, so I kept at it. It quit again and won't fire. I get no spark - even trying with the drill.

Here are some pics...not sure what all you needed to help @MartDalb but here is a start. Let me know if something else would be useful.

(Plug is new...tried another plug too)

Thanks for any thoughts anybody can offer!

View attachment 1010405View attachment 1010406View attachment 1010407View attachment 1010408View attachment 1010409

Sorry for late reply, been out and busy.
That model is mine exactly, old version (early version mtronic).
Good pictures, and that saw is clean, I would not expect it to be dirt/crud etc. But make sure to check connections of course.

No spark?, and If you have tested with
new working spark plug
checked wires all around
harness is fitted
check coil > flywheel distance and flywheel condition

As all the solid advice from everyone in this threads gives, it is most likely a dead "control unit", aka. ignition coil.

I can only refer to what Stihl did to mine, and I still have the report on it.
I can also say for sure, that I have seen atleast 3 or 4 with this exact same issue, with MS261 mtronic 2014/15 versions. No spark, and no easy solution.

1. Replaced the control unit.
2. Replaced the solonoid (to green version).

After that it ran, and still does.
Expensive repair, which Stihl in my case did free of charge.

As much as I love my 261mtronic, when they fail like this, it is a nightmare for any DIY.

 

[oldbuzzard]

Just some more FWIW - I live in CO and lead volunteer sawyers, most of whom are not real experienced sawyers. I provide the saws and use 261 and 261Cs almost exclusively, even though I personally usually use a Husky 550Xp. I also do all my own rebuilds and maintenance. I have probably rebuilt 20 261/261Cs.
1) If you are having trouble go right away for the solenoid. My Stihl dealer automatically upgrades the solenoid on all mtronics that come in the shop.
2) I have never had a bad coil (control unit), BUT - I have seen coils that wouldn’t fire unless you really pull the starter rope hard and fast. It took me awhile to figure this out when some of my older volunteers kept having trouble I couldn’t duplicate.
3) When it is hot, like over 85 degrees and you are working in the sun, both the Stihl mtronis and Husky auto-tunes act up. Over 90 degrees and they are barely useable.
My theory, and it is just a theory, that the programing just won’t go lean enough when you are operating high and hot - like I’m cutting at least 5000’ and the last couple of weeks at 90 degrees plus. Today we were cutting at 5000’ ASL but the high temp was 82 and we were working in the shade. All the saws ran perfect all day (especially the battery saws).

 

[ATH]

Just some more FWIW - I live in CO and lead volunteer sawyers, most of whom are not real experienced sawyers. I provide the saws and use 261 and 261Cs almost exclusively, even though I personally usually use a Husky 550Xp. I also do all my own rebuilds and maintenance. I have probably rebuilt 20 261/261Cs.
1) If you are having trouble go right away for the solenoid. My Stihl dealer automatically upgrades the solenoid on all mtronics that come in the shop.
2) I have never had a bad coil (control unit), BUT - I have seen coils that wouldn’t fire unless you really pull the starter rope hard and fast. It took me awhile to figure this out when some of my older volunteers kept having trouble I couldn’t duplicate.
....

Wouldn't that "not pulling hard enough" be ruled out when I turn it with a drill?

It makes sense to start with solenoid I guess because it is cheaper and I'd do that even if I did replace the control unit/ignition coil, right?

What is the part # I'm looking for?

 

[oldbuzzard]

Wouldn't that "not pulling hard enough" be rules out when I turn it with a drill?

It makes sense to start with solenoid I guess because it is cheaper and I'd do that even if I did replace the control unit/ignition coil, right?

What is the part # I'm looking for?

Yes I would expect using a drill to turn it over should be enough to make it spark.
Check all the wire connections at the coil to make sure they are good. I had one 261C that just drove me nuts until I noticed the two wire spade connection on the bottom of the coil didn’t have the little screw that tightens it.
I don’t know the pn of the solenoid off the top of my head but they are so common that all you have to do is tell the dealer you want a solenoid. Or you can buy them on eBay. You don’t want a black solenoid, you want a green or white. Also make sure you get the “kit” which includes the orange fuel filter (finer mesh to keep really small debris out of the solenoid). At my dealer that is about $40.
Replacing the coil is the LAST thing I would do because it is pricey and, IMHO, not failure prone. Check everything else first.

 

[MartDalb]

Just some more FWIW - I live in CO and lead volunteer sawyers, most of whom are not real experienced sawyers. I provide the saws and use 261 and 261Cs almost exclusively, even though I personally usually use a Husky 550Xp. I also do all my own rebuilds and maintenance. I have probably rebuilt 20 261/261Cs.
1) If you are having trouble go right away for the solenoid. My Stihl dealer automatically upgrades the solenoid on all mtronics that come in the shop.
2) I have never had a bad coil (control unit), BUT - I have seen coils that wouldn’t fire unless you really pull the starter rope hard and fast. It took me awhile to figure this out when some of my older volunteers kept having trouble I couldn’t duplicate.
3) When it is hot, like over 85 degrees and you are working in the sun, both the Stihl mtronis and Husky auto-tunes act up. Over 90 degrees and they are barely useable.
My theory, and it is just a theory, that the programing just won’t go lean enough when you are operating high and hot - like I’m cutting at least 5000’ and the last couple of weeks at 90 degrees plus. Today we were cutting at 5000’ ASL but the high temp was 82 and we were working in the shade. All the saws ran perfect all day (especially the battery saws).

solenoid is cheap(ish), sounds like something I would try first for sure.
Solid advice here.

 

[MartDalb]

You will have to excuse my poor "paint" editing skills here.
But see attached picture for solenoid colors and their part nr.

Added note. Make sure that the area around and within the solenoid placement is cleaned out, extremely well.
Note. Better fuel filter is part nr. 0000 350 3518 as @oldbuzzard mentioned.

 

[huskihl]

The solenoid kit with the orange fuel filter is cheaper than just the solenoid

 

[MartDalb]

I will add, I did buy that kit, with the white solonoid+filter, and that did NOT fix my issue with no spark.
After I got it back from Stihl service, they had changed the white solonoid to the green version. I am not saying yours need the green, just adding my story.

 

[ATH]

I will add, I did buy that kit, with the white solonoid+filter, and that did NOT fix my issue with no spark.
After I got it back from Stihl service, they had changed the white solonoid to the green version. I am not saying yours need the green, just adding my story.

I ordered the white because I could find it online without having to try to make it to dealer while they are open and I'm trying to work... I didn't find the green online. Saw a reference somewhere indicating it has been discontinued.

 

[oldbuzzard]

Solenoid color is confusing. My understanding is this:
Black came first. They are bad.
Second came green but they were dropped for white.
Then they went back to green.
Maybe we have a Stihl dealer here to comment?

 

[MartDalb]

Solenoid color is confusing. My understanding is this:
Black came first. They are bad.
Second came green but they were dropped for white.
Then they went back to green.
Maybe we have a Stihl dealer here to comment?

I can confirm that the "white" has has the Stihl MS261 mtronic listed as "the" replacement part number, meanwhile the "green" does not even show to fit the MS261 mtronic, but only models as 241cm 362cm etc.
But, since mine was fitted with a green less than a year ago, i'd say even Stihls own lists does not cover all the minor details to every model number/edition.

 

[DND 9000]

Both are listed there and it depends on the control unit firmware version which valve can be used.

 

[jacrider]

I had same intermittent issues - easy cold start, but once having run for a while, it wouldn't start hot.

Went to my Stihl dealer and he looked at the serial# and gave me a green solenoid. I have an older Version 1 m-tronic. 5 minute task for me to swap it out. Saw runs like a champ again.

 

[ATH]

how long ago was that @jacrider ?