Abstract: In a Power Propelled Reciprocating Piston Pump Liquid Sprayer, there is a reservoir which is mounted on a frame to whose cross members wheels are attached by which the reservoir with its contents is propelled forward. The power unit mounted on the reservoir can be either electric or the gas powered engine type, it drives both the sprayer and the reciprocating piston pump mounted at the base of the reservoir. The pump employs a spring tensioned rubber piston with manual adjusting mechanism and is reciprocated by a power driven crank. On the induction stroke liquid in the reservoir is drawn through the sliding disc valve into the cylinder, on compression, contents is forced through a spring ball loaded valve into a separate chamber situated within the reservoir. From the chamber runs a tube to the exterior of the reservoir where a flexible hose is attached with a spray nozzle on the end.