Abstract: A fluid pump dispenser has a pump body including a pump cylinder defining a pump chamber with a valve controlled product inlet passage leading to the chamber, a manually reciprocable pump plunger having a hollow stem defining a discharge passage leading from the chamber, a pump piston mounted on the inner end of the stem for relative sliding movement, the body having a plunger return spring for biasing the plunger into a raised position, the piston being limited for relative sliding movement between discharge open and closed positions, the piston having an annular projection defining a discharge valve seated in an annular groove of a plug element fixedly mounted to the stem at its inner end. A lost-motion effect is created between the piston and the stem which closes the discharge valve during the pressure stroke and opens the discharge during the intake stroke.