Mtronic fuel solenoid going bad?

[pro94lt]

I've got a ms241 that's started acting up, or so I think. It starts fine, cuts fine but at idle it's really really rich, and now has a bad hesitation coming off idle. It's as if all it would need is 1/2 a turn on the l jet... Thoughts?

 

[TJ the Chainsaw Mechanic]

How long have you been running the saw?

 

[foragefarmer]

I have had

I've got a ms241 that's started acting up, or so I think. It starts fine, cuts fine but at idle it's really really rich, and now has a bad hesitation coming off idle. It's as if all it would need is 1/2 a turn on the l jet... Thoughts?

I have had this problem with my 241.

Pull the spark screen. Is it clogged with carbon?

 

[foragefarmer]

For mine it was not the solenoid. It was a carb issue. Either the needle or diaphragm. I put a new carb in but a kit would have likely solved it. I needed it up and running for my business.

 

[Cobby08]

Have you tried re-calibration? I would try that first as the only investment would be time.

 

[Mastermind]

I've heard of several issues with the 241 from bogging to flooding.

I'd follow @foragefarmer and say check the spark screen first.

The solenoid usually acts boggy when it's acting up.

 

[pro94lt]

I got it in December of 2014 and I've used the piss out of it almost daily.

Its got no screen, I removed it when I got it...

I recalibrated it, but I did leave the bar on???

It started while I was clearing a long fence row of 3 inch cedars, i was probably never in the throttle for longer than 3 seconds for an hour straight...

 

[foragefarmer]

I've heard of several issues with the 241 from bogging to flooding.

I'd follow @foragefarmer and say check the spark screen first.

The solenoid usually acts boggy when it's acting up.

If the spark screen is carboned it is an indicator of a problem not the problem.

I replaced the solenoid first with little to no improvement. Took it to the dealer they said mtronic tested clean and I was running bad gas. Disagreed vociferously with their diagnosis. Still had the problem. Noticed fuel pooled in the crankcase. Bought a carb from another dealer problem solved.

 

[Redbull661]

IMO, "reset" it. when saw is cold or hasn't been run yet for the day.

I do it with bar and chain on, chain brake off of course. I hold the saw while I do the reset. I make sure the gas is topped off before I do it.

start on choke - don't touch the trigger. let it run on choke...stop watch it for 1:30-1:40. Then, Push lever all the way off in one motion.

next

just start it and let it idle. Don't touch the throttle at all. May take a few tries to get it started. May idle funny for first 10-20 seconds. just let it idle...stop watch it for 1:30-1:40. push lever all the way off in one motion.

next

start it and do 5 cuts but don't really get on it. (I can actually feel the saw improve with each of the 5 cuts.) your done. May take a tank or 2 for it to really get back to normal.

If still doing it after above reset and running 3 tanks. Then yes, you have a problem. But this is the very first thing I would do before diving into all the possible fixes. We've seen a number of guys spend A LOT of time and money trying figure out this type of problem on the mtronic. So I'd go the reset route, done with military precision, first. Just my two cents.

 

[pro94lt]

Well it looks like I jumped the gun on posting. I recalibrated it yesterday and ran it in some 20 inch logs for half a dozen cuts or so and it was still acting up. Just took it out and buried it for a dozen cuts or so and I can't make it stumble and is idling like it used to. Do you guys think the idling and making only small cuts for a hour or so did it? I love this saw!

 

[sawmikaze]

My muffler modded 241 did this for a short time and a reset seemed to cure it , the ported one doesnt seem to but i dont run it as much , im curious to see what you find.

 

[DND 9000]

Maybe your solenoid valve isn`t sealing properly. There is a little o-ring on the valve, maybe that`s the problem. This little o-ring isn`t availible from Stihl as a spare part on the m-tronic models. But on the MS 280i there was also a solenoid valve in the carburetor HD-39. In the IPL of the MS 280i this o-ring sealing the solenoid valve is availible as a spare part (9645 945 3001 O-ring 7x0.8). I think this o-ring will also fit the current m-tronic solenoid valves.

 

[DND 9000]

Just as clarification: As I`ve learned now, the little o-ring in my previous post is not the problem when an m-tronic machine is stalling at idle. Normally the valve itself is leaking and gives a rich condition for the engine. The dealer can test, if the solenoid valve is leaking by performing a pressure test.

If the sealing ring around the solenoid valve is damaged through the removal process or a other reason, it can be replaced with the part you can find in my previous post. But this is not the reason for a leaky solenoid valve, the reason is a faulty leaking valve that has to be replaced.

 

[Duane(Pa)]

FYI this is a pretty old thread n stuff...

 

[pro94lt]

Old thread but the 241 is still going strong... all it's needed is multiple bars, some flippy caps and spur sprockets from use... my only complaint to date now is it takes 6 or 7 pulls to crank when cold, once warm it's one pull and it's going... it really is a amazing saw to use.

 

[Ketchup]

I read this in April when I was trying to diagnose my 201t mtronic problem. I know nothing about the 241, but the O-ring for the 280i (listed above) DOES NOT FIT a 201t Mtronic solenoid. I lost the thread back then, but just found it again, so hopefully this info is helpful to someone.

FYI: My 201t Mtronic is now flooding again after replacing the original Solenoid in May (8 months ago). The Solenoids are expensive junk.

Sorry for the hijack.

 

[DND 9000]

How exactly does that O-Ring not fit the current 0000 120 5110 black m-tronic solenoid valve? I have both valves (the old one for the MS 280i and the current m-tronic black one here.) They have the same dimentions including the O-Ring. Please elaborate on it.

 

[redlight066]

There is one solenoid for the entire lineup. 201tc all the way up to 661. Failing solenoid will demonstrate these symptoms

1. Slightly lower idle speed and struggles to maintain constant idle speed. (will eventually load up and stall but not always)
2. Very difficult to restart when hot

Other symptoms that are less common include bogging when trying to rev it and lean/hot at WOT.

Always check the fuel filter and be sure it is free flowing and unrestricted. Blow through it. Clean fresh filter is needed. Remember it's constantly adjusting fuel settings. No way that can happen with restrictions in flow. It will fight itself trying to compensate.

A fouled/ dirty plug will also hamper performance. Expect solenoids to last 200-300 hours. Another test for the solenoid is removing the fuel filter and pressure testing the solenoid. 5lbs of pressure with no leak down

 

[redlight066]

I read this in April when I was trying to diagnose my 201t mtronic problem. The Solenoids are expensive junk.

Sorry for the hijack.

Yes solenoid is now 49.95 at your local dealer. Used to be $18. You can find a new mtronic carb on line for less. Harvest the solenoid CAREFULLY. I've bought NEW carbs for $25 including shipping on eBay.

Hope this helps. Rich

 

[DND 9000]

There is one solenoid for the entire lineup. 201tc all the way up to 661.

Yes, that`s correct. It`s also used on the m-tronic clearing saws. The newer versions of the MS 362, 462 and 661 with m-tronic v.3 have the newer white solenoid valve. The first versions of the MS 462 C-M with 1142 400 4702 control unit and carburetor 1142/01 + 1142/02 had the black solenoid valve.