There are products at your local auto parts store such as Epoxy Ribbon, JB Weld, and others that don't require heating you can use to patch the leak. Be sure and follow the directions on the package.
You can't BEAT KENT'S ALL IN ONE.
on the fuel line running from the tank to the carb.
There will be an inline filter on the fuel supply line from the tank to the carburetor
fill tank, to top of neck, watch the leak area, [don,t start it]
believe it or not,I used a Turkey Baster to drain my tank to change a fuel filter.
from around the fuel cap or the fuel can you use to fuel it. if it is a metal fuel tank then you can get rust built up in it and it starts to flake off
Fuel tank cap vent is plugged.
it may not have one. If it does it will be located on the fuel line between the fuel tank and the carburetor.
add a fuel treatment to remove water if it is a small amount or drain the fuel and replace with fresh
it will probably explode or it will burst into flames either or its bad
If you tilt the mower to get at the blade for sharpening, or go down a particularily steep slope, gas will run from the tank out through the filter.
That will vary for each make and model of mower.
There are several things that can cause your fuel tank to leak. The most common cause is a hole in the fuel tank. A loose fuel line can cause the fuel tank to leak.