A pressure washer (110; 900), comprising: a prime mover; a water pump coupled to the prime mover, the water pump including a pump inlet for receiving fluid from a common fluid source and a pump outlet for supplying a pressurized primary fluid; a chemical source for supplying chemicals; a jet pump including a primary fluid inlet fluidly coupled to the pump outlet, a secondary fluid inlet configured to be coupled to the fluid source, a fluid outlet, a mixing chamber fluidly upstream of the fluid outlet and fluidly coupled to the secondary fluid inlet, a nozzle having a restriction, wherein the nozzle is fluidly coupled between the primary fluid inlet and the fluid outlet so that the pressurized primary fluid flows through the restriction prior to entering the mixing chamber, an outlet passage between the mixing chamber and the fluid outlet, the outlet passage including a step, wherein a diameter of the outlet passage is at a minimum diameter at the step and is at an exit portion diameter greater than the minimum diameter at an exit portion downstream of the step, and a chemical inlet fluidly coupled to the outlet passage downstream of the step to selectively provide chemicals from the chemical source to the fluid flow exiting the fluid outlet of the jet pump; and a spray gun (118; 700, 740, 750; 760) configured to be fluidly coupled to the fluid outlet of the jet pump, the spray gun (118;700, 740, 750; 760) including a spray gun outlet having a variable effective flow area; wherein, in operation, a first effective flow area of the spray gun outlet creates a first back pressure at the jet pump, thereby implementing a high pressure operating mode in which the pressurized primary fluid flows through the jet pump and exits through the fluid outlet of the jet pump; wherein, in operation, a second effective flow area of the spray gun outlet that is greater than the first effective flow area creates a second back pressure less than the first back pressure at the jet pump, thereby implementing a high flow operating mode in which the pressurized primary fluid flows through the jet pump and entrains a secondary fluid supplied through the secondary fluid inlet from the common fluid source so that the secondary fluid also flows through the jet pump, resulting in a combined fluid flow of the primary fluid and the secondary fluid exiting through the fluid outlet of the jet pump; and wherein the step is structured as a venturi such that at a first pressure of the fluid flow through the venturi, chemicals from the chemical source are added to the fluid flow prior to exiting the fluid outlet of the jet pump, and at a second pressure greater than the first pressure, chemicals from the chemical source are not added to the fluid flow prior to exiting the fluid outlet of the jet pump. a prime mover; a water pump coupled to the prime mover, the water pump including a pump inlet for receiving fluid from a common fluid source and a pump outlet for supplying a pressurized primary fluid; a chemical source for supplying chemicals; a jet pump including a primary fluid inlet fluidly coupled to the pump outlet, a secondary fluid inlet configured to be coupled to the fluid source, a fluid outlet, a mixing chamber fluidly upstream of the fluid outlet and fluidly coupled to the secondary fluid inlet, a nozzle having a restriction, wherein the nozzle is fluidly coupled between the primary fluid inlet and the fluid outlet so that the pressurized primary fluid flows through the restriction prior to entering the mixing chamber, an outlet passage between the mixing chamber and the fluid outlet, the outlet passage including a step, wherein a diameter of the outlet passage is at a minimum diameter at the step and is at an exit portion diameter greater than the minimum diameter at an exit portion downstream of the step, and a chemical inlet fluidly coupled to the outlet passage downstream of the step to selectively provide chemicals from the chemical source to the fluid flow exiting the fluid outlet of the jet pump; and a spray gun (118; 700, 740, 750; 760) configured to be fluidly coupled to the fluid outlet of the jet pump, the spray gun (118;700, 740, 750; 760) including a spray gun outlet having a variable effective flow area; wherein, in operation, a first effective flow area of the spray gun outlet creates a first back pressure at the jet pump, thereby implementing a high pressure operating mode in which the pressurized primary fluid flows through the jet pump and exits through the fluid outlet of the jet pump; wherein, in operation, a second effective flow area of the spray gun outlet that is greater than the first effective flow area creates a second back pressure less than the first back pressure at the jet pump, thereby implementing a high flow operating mode in which the pressurized primary fluid flows through the jet pump and entrains a secondary fluid supplied through the secondary fluid inlet from the common fluid source so that the secondary fluid also flows through the jet pump, resulting in a combined fluid flow of the primary fluid and the secondary fluid exiting through the fluid outlet of the jet pump; and wherein the step is structured as a venturi such that at a first pressure of the fluid flow through the venturi, chemicals from the chemical source are added to the fluid flow prior to exiting the fluid outlet of the jet pump, and at a second pressure greater than the first pressure, chemicals from the chemical source are not added to the fluid flow prior to exiting the fluid outlet of the jet pump.