Stop fuel drips, boost performance, and stay safe. Us mechanics would pressure/vacuum test the carburetor with a cute little hand air pump called a mighty vac to narrow down the issue after verifying the engines condition with a quick compression test. The role of fuel pressure another factor that can contribute to gas leakage is fuel pressure
Stihl gas cap failure : Chainsaw
When a stihl chainsaw is running, the fuel pump creates pressure in the fuel system to ensure proper atomization and combustion
However, when the saw is on its side, this pressure can cause the fuel to seep out of the tank and carburetor.
Have a ms171 bought in 2012 and has never been serviced It just started leaking gas when put on its side (see pic) I noticed it starts to leak when the fuel rises to a small black nipple (see pic with red circle) If you tilt the chainsaw to submerge the nipple it leaks
Stihl chainsaw leaking gas « reply #1 on February 17, 2023, 06:29:37 pm » this is where the tank vent tube attatches and has somr grub screws to stop it from leaking out while at the same time allowing air back into the fuel tank to prevent a vacume lock logged Could be leaky fuel line/tank grommet/tank vent, leaking from the carb through a leaky inlet needle or gasket, or possibly a leaky gas cap seal
