Abstract: A control mechanism functions as a dual stage controller that is alternately and independently responsive to engine oil pressure and intake manifold pressure to adjust fuel delivery by one or more unit pumps. Engine oil pressure is delivered as a control input to one end of a piston bore. Manifold air pressure acts on a diaphragm to deliver another control input which acts on a control piston disposed for reciprocation in the bore. The diaphragm and associated control rod are axially opposed to the end of the bore to which engine oil pressure is delivered. During engine start up, oil pressure is low and a spring bias moves the control piston in a direction to increase fuel delivery. During start up, the control piston position is dependent upon engine oil pressure independent of manifold air pressure. After start up, the control piston position is a function of manifold air pressure independent from engine oil pressure.

Abstract: A control mechanism functions as a dual stage controller that is alternately and independently responsive to engine oil pressure and intake manifold pressure to adjust fuel delivery by one or more unit pumps. Engine oil pressure is delivered as a control input to one end of a piston bore. Manifold air pressure acts on a diaphragm to deliver another control input which acts on a control piston disposed for reciprocation in the bore. The diaphragm and associated control rod are axially opposed to the end of the bore to which engine oil pressure is delivered. During engine start up, oil pressure is low and a spring bias moves the control piston in a direction to increase fuel delivery. During start up, the control piston position is dependent upon engine oil pressure independent of manifold air pressure. After start up, the control piston position is a function of manifold air pressure independent from engine oil pressure.