A pump system includes pump having a control feature which, responsive to a supply of pressurized working fluid, reduces the pressure of the working fluid pressurized by the pump. The control feature is connected to the output of the pump by a regulating valve. The control feature receives pressurized working fluid to decrease the output of the pump in response to the pressure of the supplied working fluid. A regulating valve selectively connects the pressurized working fluid to the control feature. The regulating valve has a control port to receive pressurized working fluid from the pump to urge the valve to a closed position against a biasing force. A controllable valve is operable to interrupt the supply of pressurized working fluid to control port to alter the output pressure of the pump.