Fuel supply system for an internal combustion engine

Claim 1

A fuel supply system for an internal combustion engine comprising: a carburetor including an air passage, a float chamber, and a fuel spray nozzle disposed within said air passage and connected to said float chamber, an alcohol-containing main fuel tank connected to said float chamber, a fuel pump in the connection of said main fuel tank to said float chamber, and a gasoline-containing auxiliary fuel tank, a choke valve within the air passage of the carburetor, upstream of said fuel spray nozzle, a gasoline supply diaphragm device, including a hollow casing and a diaphragm member within said hollow casing, which defines a first chamber vented to the atmosphere, and a second chamber, a first conduit connecting said second chamber to said auxiliary fuel tank, a second conduit connecting said second chamber to said float chamber, first and second one-way valves interposed in said first and second conduits respectively, preventing flow of fuel from the second chamber to the auxiliary fuel tank and from the float chamber to the second chamber, a choke valve actuating mechanism including mechanical connecting means extending between said choke valve and said diaphragm member of the gasoline supply device; whereby said mechanical connecting means causes displacement of said diaphragm member towards a position in which said second chamber has a minimum volume, when said choke valve is displaced towards its operating position during starting and warming up of the engine.