If you’re having trouble beginning your Stihl door, a blocked carburetor is one of the possible factors. The probability that it’s causing the problem increases the age of the fuel at the gas tank. Old fuel leaves deposits at the carburetor fuel lines which slow the flow of gasoline into the combustion chamber. If the trimmer is old enough, the carburetor may need rebuilding, but if that’s necessary, it is usually just as cost effective to replace it. It is possible to give the carburetor a good cleaning before removing it from the trimmer.
Open the air filter cover. Most Stihl trimmers have a screw which discharges the cover — only turn it counterclockwise using a screwdriver. Remove the air filter and clean it, if necessary. Leave it out of the trimmer.
Spray the parts of the carburetor which you are able to see beneath the air filter with carburetor cleaner. The cleaner emulsifies grime and old oil. Brush it away using a cotton swab.
Spray a generous amount of carburetor cleaner to the air intake port, and depress the throttle activate a few times to work with the cleaner through the internal carburetor mechanisms. Open and shut the choke to clean the choke valves.
Prime the carburetor by pushing the priming bulb three or four times, and then shut the choke and pull on the beginning cord to begin the engine. Set the choke into the “run” position once the engine starts. Spray two or three brief squirts of cleaning fluid to the air intake port. The carburetor will pull the fluid through the combustion chamber fuel ports and tidy them. The engine will surge when you do so.
Turn off the engine, and then replace the air filter. Cover and then start the engine. If the engine is still hard to start, repeat the cleaning procedure.