Patent ID: 6973922

Claim:
A fuel supply control system for an engine, including a composite control valve which is constructed by a valve housing, first and second diaphragms disposed to be opposed to each other with their peripheral edges secured to the valve housing, a negative pressure working chamber defined between the first and second diaphragms to communicate with a negative pressure generating section in the engine, a first control valve connected to the first diaphragm and adapted to be opened and closed by advancing and returning of the first diaphragm due to generation and extinction of a negative pressure in the negative pressure working chamber, and a second control valve connected to the second diaphragm and adapted to be opened and closed by advancing and returning of the second diaphragm due to the generation and extinction of the negative pressure in the negative pressure working chamber, the first control valve being incorporated into an air vent system which provides communication between an upper space in a fuel tank and the atmosphere, the second control valve being incorporated into a fuel passage system which provides communication between a portion of the fuel tank below a fuel oil surface and a fuel supply section in the engine.