Abstract: A pressure washer includes a prime mover, a pump driven by the prime mover, and a spray gun fluidly coupled to the pump. The spray gun includes a flow-control valve movable between an open position and a closed position to control a fluid flow from the spray gun, a user interface for controlling the flow-control valve, a sensor configured to detect the state of the user interface, and a first wireless system electrically coupled to the sensor. In a first state of the user interface, the flow-control valve is in the closed position. In a second state of the user interface, the flow-control valve is in the open position. The pressure washer further includes a second wireless system electrically coupled to the prime mover. The second wireless system signals the prime mover to start to drive the pump to provide fluid to the spray gun upon receiving a start signal from the first wireless system indicating that the sensor detects the user interface in the second state.