Pressure regulator for injection systems for internal combustion engines

A pressure regulator for internal combustion engine injection systems comprising a metal casing, a diaphragm secured within said casing and dividing the interior into a first chamber and a second chamber, a first duct in said casing adapted to communicate said first chamber with an intake manifold, a second duct in said casing adapted to communicate said second chamber with a pump, a third duct in said casing adapted to communicate said second chamber with fuel injectors, and a fourth duct in said casing having an inlet extending into said second chamber adapted to communicate said second chamber with a fuel tank, closure means operatively associated with said diaphragm for opening and closing said inlet of said fourth duct, said closure means comprising a hemispherical valve member having a spherical portion and a flat surface, a support means connected to said diaphragm and having a recess therein opposed to said inlet of said fourth duct for rotatably receiving said spherical portion of said valve member with said flat surface facing said inlet and means for biasing said spherical portion of said valve member into contact with said recess, said spherical portion having the center thereof lying in the plane of said flat surface, said means for biasing said spherical portion into contact with said recess is comprised of a coil spring surrounding said fourth duct and engaging said flat surface.