Variable venturi type carburetor

A variable venturi type carburetor of an internal combustion engine, comprising:

• a housing;
• a bore extending through said housing and having an inner wall defining an intake passage;
• a suction piston movably mounted in said housing and having a bottom end face projecting into said intake passage, said bottom end face of said suction piston and said inner wall of said intake passage defining a venturi, said suction piston moving up and down in response to a change in the vacuum produced in said intake passage downstream of said venturi for maintaining the velocity of air flowing into said venturi at a constant value;
• a jet disposed on the inner wall of said intake passage at a position facing said bottom end face of said suction piston;
• a needle fixed onto said bottom end face of said suction piston and entering into said jet, said jet and said needle defining an annular opening throough which fuel is injected into said intake passage;
• a fuel reservoir;
• a fuel recirculating pump having a suction side;
• a fuel recirculating passage communicating said fuel reservoir with the suction side of said fuel recirculating pump;
• a restricted opening disposed in said fuel recirculating passage for forming a vacuum zone in said fuel recirculating passage located between said restricted opening and the suction side of said fuel recirculating pump, and;
• a fuel supply passage communicating said vacuum zone with said jet.