Small Engines (Lawn Mowers, etc.): lawnmower fuel system, external fuel, hi mike

Question
what could be causing gasoline to flow into the air filter housing?

Answer
Hi Mike-
If the tank is higher than the carb, and the float isn't working properly, that would do it.

If the Mower has an external fuel pump, and the float isn't working properly, that would do it.

Check the float.  Drop the bowl, and make sure you can control the flow of gasoline into the carb by raising and lowering the float.
Lemme know how this goes ok?