Stihl Garden - Page 7 - Recent Questions, Troubleshooting & Support

Check fuel tank vent, loosen fuel cap as a test. By your description it is running only on the fuel available from being primed. So likely carburetor impulse air or diaphragm (carb rebuild or replace).

Could be that it's stopping because it's going to sees up. Ecsesive pkay on piston rings

Air fuel mix screws need adjusting

clean rebuild or replace carb

There should be a small hole on the top of the strimmer head. Put a small screwdriver in the hole as far diwn as you can then spin the head till the screw driver drops down a little more . Once you have done that the hole head will unscrew.

Hold the blue piece firmly with your left hand, to keep it still. twist the red piece counter clockwise with your right hand, remove the spool of trim line Then remove the deflector marked in blue, by loosening the bolt marked in red. is this as far as you needed to go? If you want to go further Loosen the large bolt marked in red, this will release the drive shaft marked in purple, then remove the bolt marked in green and there is one more screw on top that is a short set screw that will need to be removed then you can remove the actual head of the trimmer . GoodLuck!!!

possible cracked fuel line or cracked bulb.

Prime the primer ball.

Clean the spark arrester screen! It’s amazing how dirty they can get - I clean mine with a dremel and a wire type brush. Once the screen is cleaned and replaced, the blower will run great! I found this trick last year and it saved me a repair bill.

https://www.stihlusa.com/WebContent/CMSFileLibrary/InstructionManuals/STIHL-FS-38-Owners-Instruction-Manual.pdf

No "gear box" on a curved shaft trimmer. Please peruse the diagrams at following link. https://www.diyspareparts.com/parts/stihl/diagrams/fs38-z-2-mix/ You want to remove what?

Sounds like lack of fuel. Try backing the air fuel mixture screw back 2 turns and see if it helps. Once it starts, see if you can keep it running by spraying carb cleaner into the carb. If you can keep it running long enough, place the palm of your hand over the carb inlet to choke the carb causing a sudden suction in the carb. Some times this will dislodge foreign material and help it run.

the best way i have found it to take the plug out and clean it. take the carburetor off and clean it with carburetor cleaner and blow the fuel line and filter out with air, clean out the fuel tank. put it back together and it should run like new. if you are having that many problems sometimes it is best just to clean the whole system. be sure the fuel can is labeled and be sure no water gets in the can.

could be plugged with saw dust

spark arrestors