Cleaning carb on MS 280

IXLR8 · Feb 14, 2025

I have a Stihl MS280 I bought new about 2001. It has served me well until this year when it started not wanting to run at speed. After about a month, it won't run at anything above idle. It starts fine, 2 pulls, will idle all day long, but as soon as I hit the throttle, it dies. It has run on ethanol gas since new, since that is all I had available, I suspect it has now taken it's toll and it is time to clean the carb. I have pulled carb apart and cleaned what I can, didn't look really dirty. I am guessing there is some 'gunk' in the high speed circuit. Spraying every nook and cranny with carb cleaner doesn't seem to make any difference. I have tried to pull the fuel filter, but it seems the fuel line is too short and I can't get the filter out. Unless there is a trick I am missing. I have installed new spark plug and air filter. I tried to open the jets to try and to get something sprayed thru them. I can't open the high speed jet any further and I can only open the low speed jet 1/2 a turn. I am neurvous adjusting the jets too much as I am TERRIBLE tuning a 2 cycle engine and I know how critical it is to get it right. Any suggestions to better clean the carb.

Hay Dude · Feb 14, 2025

Could be sucking air through a crack in fuel line, too.

etpm · Feb 14, 2025

My little Stihl became hard to start and ran bad. I tried Seafoam. I didn't want to take the carb apart if I didn't need to. Anyway, the Seafoam did the trick and it now starts easily again and runs well. I did need to add Seafoam to two tank fulls because even though the first use seemed to fix the problem it returned, though not as bad. After the second fill up using Seafoam the problem went away and has no returned. I was frankly not expecting the Seafoam to work, I have always been dubious of fixes in a bottle.
Eric