If any gas is leaking from your lawn mower, that is a safety hazard. The fumes can ignite from a hot exhaust and cause a fire. When you have a gas leak, it is best to get it addressed by a lawn mower repair professional immediately.
Many times the cause of this leak is the needle and seat in the carburetor is not sealing. The weight of the gas from the tank is sitting on the needle which is the size of a sharpened pencil lead. If there is any buildup of oxidation on it, it will begin to leak. It could leak out slowly or it could come out gushing and empty the tank quickly.
Garage fires have been caused by leaking lawn mowers, so be careful about paying attention to the top of your mower on a push or self-propelled and on the floor if it is a rider or zero turn.
The carburetor will need to be disassembled and cleaned or replaced if the fuel oxidation is too bad.
If you need lawn mower repair, visit our Locations page for a shop near you.