a method of controlling the speed of an engine includes positioning a throttle at an operating position between an idle position that reduces the engine speed to an idle speed , and a normal speed position at which the engine runs at a speed greater than the idle speed , collecting a fluid within a manifold , sensing a pressure within the manifold , and adjusting the operating position of the throttle in response to the sensed pressure . when the sensed pressure is low , the throttle is moved toward the idle position and when the pressure is high , the throttle is moved toward the normal speed position . the method further includes positioning an unloader downstream of the manifold , the manifold configured in one of a first position in which the unloader directs fluid from the manifold to the pump , and a second position in which the unloader directs fluid to a point of use .