I have a Stihl MS-250 I bough new about 4 years ago. It has been running great. I have been trimming a lot of Juniper trees recently, and it has performed super, starting easily each day. I killed it at the end of the day recently, and the very next day it wouldn't fire at all. It was externally pretty dirty, so I cleaned it well and it fired up and ran okay. I killed it, expecting to use it the next day, but it wouldn't start again. It seemed to have no spark so I ordered an ignition module and installed it. It still wouldn't start. It does have spark now, but still doesn't run. I haven't taken the carburetor off yet. Any ideas? I do use conventional (no ethanol) gasoline.
Does compression feel normal? Did you try a new plug?
Easy things first- new plug, clean air cleaner, check for no obstruction in exhaust, fresh gas, check for spark which you said you did. at this point it should fire off with a little gas in throat of carb.
Don't forget to check the kill switch for sticking, or shorting.
JJ
I took the muffler off and there was liquid inside the cylinder, but not very much. I wonder if it could have gotten flooded when I was repeatedly cranking it when it had no spark, and maybe I just need to leave it open for a day or two, then put it back together and try again now that I have spark. Thanks for all the replies. If it still doesn't start I'll try rebuilding the carburetor.
Only choke (ignition switch all the way down) a MS250 for 2-3 pulls max even if you don't hear it burp. Otherwise it WILL flood.
Usually with a flooded saw you can usually start it by holding the throttle wide open no choke and give it a few pulls, once the saw starts hold it wide open a bit to clean out the extra fuel.
If that doesn't work remove plug and and pull it over with throttle wide open and no choke then replace with fresh plug.
Thanks for all the replies. I finally decided to take the carburetor apart and clean it and make sure all the little passages were clear. It started and ran good as new. I had assumed that since it was running great the previous day, the carburetor was in good shape. Wrong. Thanks again.