Abstract: A relatively simple pump assembly for use in a sprayer includes an elongated cylinder for mounting in a sprayer container, a plunger slidable in the cylinder, a piston on the bottom of the plunger slidably engaging the interior of the cylinder, a one-way valve in the bottom of the plunger for transferring air from above to beneath the piston during upward movement of the plunger, a second one-way valve normally closing the bottom of the cylinder for discharging air therefrom into the container to pressurize the container when the plunger and piston are reciprocated in the cylinder, a cap closing the top of the cylinder and retaining the plunger therein, a handle on the upper outer end of the plunger for movement from a latched position in which the handle can be used to carry the sprayer, and a use position in which the handle can be used to reciprocate the piston, and a sleeve on the top end of the cylinder, the sleeve having threaded bottom and top ends for (i) mounting the pump assembly in a container and