You will have to find where it is leaking. Sometimes from the carburetor if so you will have to remove and clean the carb. and may have to adj. or replace the fuel metering plunger. Other times the hoses between the carb. and the tank have holes which allow leakage. Back in the 90s Stihl had problems with the hoses and had to replace many, some are still in service. Another thing could be hole in gas tank which is unusual but could happen. If this is the problem you will have to remove all old fuel, clean tank thoroughly with carb. cleaner, blow out with compressed air and then repair hole with a good oil resistant epoxy such as J B weld.
A leek.
Leek is a noun.
Leek to Manchester is 30.8 miles.
Leek moth was created in 1839.
Leek's Lodge was created in 1927.
Stephen Leek was born in 1959.
Andy Leek was born in 1964.
Kate Leek is 5' 2".
A homophone for leek is leak.
The latin translation for Leek is Allium porrum.
It's a leek
Tagalog Translation of LEEK: tagas