US Patent 7757670 Fuel supply system for general purpose engine

A fuel supply system for a general purpose internal combustion engine is equipped with a sub-fuel tank that retains gasoline fuel supplied from a main fuel tank and houses the high-pressure pump in its interior. In other words, the pump is immersed in the gasoline fuel retained in the tank, so that if an air pocket should occur in the fuel supply pipe between the main fuel tank and pump, the air will be discharged from the sub-fuel tank to the exterior through a fuel return pipe etc., thereby ensuring that the pump does not suck in air. Since fuel injectors can therefore inject gasoline fuel immediately, starting performance is enhanced.