Engine configured to drive a diaphragm fuel pump using pressure fluctuation in a crank chamber of the engine

An engine having a structure of a four-stroke engine, the engine comprising:

• a piston configured to reciprocally move;
• a crank chamber in which pressure fluctuation occurs by the piston moving reciprocally in the crank chamber;
• a carburetor including a diaphragm fuel pump, the diaphragm fuel pump including:
• a pump chamber configured to suck in and eject fuel;
• and
• a diaphragm chamber to which a pressure that drives the pump chamber is supplied;
• a single communicating path configured to allow communication between the diaphragm chamber and the crank chamber;
• and
• an opening of the communicating path in the crank chamber side, the opening being formed near a position in which a termination portion of a skirt part of the piston is located when the piston is located at a top dead center such that the piston opens and closes the opening, wherein
• the piston closes the opening of the communicating path when a positive pressure is created in the crank chamber and opens the opening to supply substantially only a negative pressure from the crank chamber to the diaphragm chamber via the communicating path, and
• the opening is not open in a combustion chamber formed by a cylinder part and an upper portion of the piston.