Abstract: A fluid dispenser pump having a piston extending from one end of a cylinder with resilient means urging the piston from the cylinder to its extended position for manual movement into the cylinder to its retracted position, said piston and cylinder being elastomeric plastic members, with complementary cylindrical walls forming a sequence of chambers. An inlet chamber communicates with a fluid supply. An auxiliary pressure chamber is normally sealed from the inlet chamber, but it communicates with the inlet chamber whenever the piston is at its fully extended position. An operating chamber communicates with the auxiliary pressure chamber and a first check valve means between the chamber permits flow from the auxiliary pressure chamber to the working chamber, but prevents a reversal of such flow. A discharge chamber communicates with the working chamber and a second check valve means between the chambers permits flow from the working chamber to the discharge chamber but prevents a reversal of such flow.