Pull the spark plug connector off the spark plug. Remove the spark plug using a ratchet. This prevents sparks.
Locate the fuel line running between the fuel tank and the carburetor.
Loosen the screws on the clamps holding the fuel line to each end. Pull the fuel line off the unit.
Blow the inside of the fuel line with a can of compressed air to remove any dirt from the inside of the line.
Place the fuel line back on the mower and tighten the clamps. Reinstall the spark plug and start the unit to test it.