MS 250 wont shut off

Grant1994 · Sep 18, 2011

Have a three year old MS 250 that I use for small cutting and limbing, my other saw is a 290 I love both of them but latley the 250 won't shut off. I flip the switch up to stop and it just keeps running the only way I can get it to stop now is let it run out of gas but if it full I hve to deity it to choke and rev it up and it dies, however this method can not be good for the saw.
If you guys could help me try to self diagnose this because last time I took my saw in for service it took three weeks to get back and I can't be without it for that long now I'm doing all of my cutting for next years wood.
Thanks!

Ironhand · Sep 19, 2011

If you can chase the wiring from the on/off switch, check to be sure that the ground wire is not broken or disconnected.

xyz123 · Sep 19, 2011

Seen that on a MS250 I worked on a week or so ago. The metal wire end that goes in the BLACK plastic master control switch area had came out. Just slide in back in the groove, if that is your problem too.

Must remove carb cover to see left rear side.

LD1 · Sep 20, 2011

Yep, gotta get to the wiring. All the kill switch does is ground the coil so there is no spark. If one of the wires came off, or it the switch is bad, it wont stop the saw.

And I will add though, there is no harm in choking the saw to kill it. All you are doing is basically flooding the saw. Making the Mix too rich to burn. It wont hurt the saw at all.

Now if you were pinching off a fuel line, and causing it to die because it went too lean, that is bad. The saw will start racing and surging and lean is not good on a 2-stroke. That is why (if you have cut long enough you will know what I am talking about) dont like running a saw until it is flat out of gas. The FIRST signs of surging becasue gas is getting low, shut the saw off. Dont try to milk the throttle through that last cut. You are running too lean and will shorten the life of the saw.

silvertramp · Sep 20, 2011

My old Stihl was doing that. Once it was a bad connection, the next time ther was enough debris built up to prevent full operation of the switch. Cleaning was all it took that time.