Abstract: A spray gun for spraying of liquids utilizing compressed air includes a molded casing which contains within a sealed pressurized portion thereof, an electric motor and an air compressor driven by it. A manual trigger sequentially controls an electric switch for the motor and a needle valve for the discharge nozzle such that the motor and compressor are started before liquid is admitted to the nozzle, and are operated after liquid flow to the nozzle has been terminated. A diaphragm-type inlet check valve communicates with a pressure chamber of variable size forming a part of the air compressor, a second diaphragm providing both the movable wall of the pressure chamber as well as the movable element of an outlet check valve built therein which conducts pressurized air into the pressurized portion of the casing, passing across the motor enroute to the nozzle.