Abstract: An auxiliary-overload-bypass valve in a fluid-delivery system including a pump having its own internal, relatively low-volume-capacity bypass valve. The auxiliary valve relieves a defined high pressure condition which can occur in the system when the pump is overworking and the system is not delivering fluid. The valve includes a valve body with an inlet coupled to the system downstream of the pump and an outlet coupled to the system upstream of the pump. Disposed inside the body is a valve-opening mechanism for allowing fluid to pass through the valve to relieve the high pressure condition.