1. Float Valve: The float valve in the carburetor controls the fuel level in the carburetor bowl. If the float valve is stuck or damaged, it can cause the fuel level in the bowl to rise too high, which can lead to flooding and gas leaking out of the carburetor and into the muffler. Check the float valve to make sure it's moving freely and not obstructed.
2. Carburetor Gasket: The carburetor gasket seals the carburetor to the engine block. If the gasket is damaged or leaking, it can allow fuel to seep out of the carburetor and into the engine. Check the carburetor gasket for damage or leaks and replace it if necessary.
3. Fuel Line: The fuel line carries fuel from the gas tank to the carburetor. If the fuel line is cracked or damaged, it can leak fuel. Check the fuel line for cracks or leaks and replace it if necessary.
4. Engine Oil Level: If the engine oil level is over the full mark, it can cause the engine to run poorly and lead to gas leaking out of the muffler. Check the engine oil level and drain any excess oil if necessary.
5. Piston Rings: Worn or damaged piston rings can allow fuel to seep into the engine oil, causing the oil level to rise and the engine to run poorly. Check the piston rings and replace them if necessary.
If you're not comfortable performing these checks yourself, I recommend taking your mower to a qualified small engine repair technician for diagnosis and repair.
