It's frustrating during the mowing season when you try starting your lawnmower, but it won't start--so you prime it and try starting it again. Repeating this process over and over will eventually flood the carburettor with gas--and the mower still won't start. Fortunately, it's not difficult to get your flooded lawnmower to start again.
Adjust the throttle to the turtle setting or the area the throttle the engine usually dies at. Pull the rope six times or turn the electric start key for 10 to 12 seconds. This will create a vacuum that forces the gas out of the carburettor and into the fuel bowl.
Search for the carburettor on the side of the engine. The fuel line is connected to the carburettor on the side. Also on the side of the carburettor is an adjustment needle that adjusts the needle valve in the carburettor when you turn it. Rotate the needle a 1/4 turn to the left, and then try to start the mower. If it doesn't start, rotate the needle a 1/4 turn to the left and try to start the engine again. If it doesn't start, rotate the needle a full turn to the right (clockwise) and try starting the engine again.
Unscrew the air filter cover. Pull the cover off and pull out the air filter. A flooded engine will spew gas out of the carburettor and onto the air filter, making it hard for the engine to suck in air for mixing with the fuel. Allow the air filter to dry for an hour in the sun or buy a new one if it is very dirty.
Insert the flathead screwdriver into the carburettor behind the air filter. When you insert the screwdriver into the carburettor, you will make the butterfly valve open up wide for maximum air intake. Try starting the mower again. Let it run and burn any gas flooded into the piston. Shut it off, remove the screwdriver and replace the air filter and cover.