Abstract: A high pressure fluid pump having a telescoping cylinder assembly disposed in a cylindrical sleeve. The telescoping cylinder assembly has a stationary member rigidly attached to the cylindrical sleeve and a telescoping member biased towards an outlet port. The telescoping member is reciprocated relative to the stationary member by the displacement of an armature in response to the intermittent energizing of a solenoid coil. An inlet valve connected to the telescoping member and an outlet valve connected to the stationary member provide a unidirectional fluid flow through the telescoping cylinder assembly with the reciprocation of the telescoping member. The outlet valve has a flat valve member which is biased against a valve seat provided at the end of the stationary member adjacent to the outlet port. The flat valve member is preferably made from a resilient elastomer which increases the efficiency of the pump and eliminates forward and back syphoning.