Umbrella check valves

A valve for use in an impulse fuel pump to supply fuel to an engine, said valve comprising:

• a body having an input side, an output side and a plurality of ports extending through said body,
• a flexible membrane having an upper side, a lower side, a peripheral edge, and a generally semi-spherical cross-section, said membrane being disposed on the output side of said body, carried by said body and responsive to fluid pressure to close and open to control the flow of fluid through said plurality of ports,
• a spherical surface having a periphery on said body at the output side thereof through which said plurality of ports extend forming a valve support surface that substantially corresponds in shape to the lower side of said membrane, and
• a generally flat seating surface on said body for engagement with the periphery of said membrane to close said ports, said body and said membrane being constructed and arranged such that when said valve is not subjected to fluid pressure, the periphery of said membrane engages said seating surface and leaves a small gap between the lower side of said membrane and said spherical surface on said body to eliminate overflexing of said spherical membrane.