Fuel injection pump and replaceable check valve therefor

A liquid fuel injection pump for supplying measured charges of fuel to an internal combustion engine comprising a distributor rotor having a transverse bore extending therethrough and a pump chamber in which the charges are pressurized to high pressure for injection into the cylinders of said engine, a transfer pump, a passage for delivering the output of said transfer pump to said pump chamber through said transverse bore, and a replaceable check valve cartridge slidably mounted in said transverse bore, said check valve cartridge comprising a prefabricated integral check valve assembly comprising a cylindrical barrel having a single diameter, a hollow valve seat secured to said barrel at one end thereof, a stop secured to the barrel at the other end thereof, a ball for seating on said valve seat, a chamber in said barrel between said valve seat and said stop, a closure piston slidably mounted within said stop and engageable with said ball for seating the ball following the filling stroke of the pump chamber, means for connecting the output of said transfer pump to a cavity at the end of said piston to urge the piston in a direction to seat the ball and means engaging both ends of said barrel for removably retaining said cartridge in said transverse bore without transmitting any transverse forces to said distributor rotor.