Abstract: A fuel supply system is provided, including a plurality of fuel injection pumps within the cylinder head on a cylinder block, a fuel manifold having a fuel supply portion and a fuel return portion external to the cylinder head and extending the length thereof, each pump having a fuel supply and outlet passage integrally formed in the cylinder head and communicating with an annular passageway about each fuel injector, each said fuel supply and outlet passage further communicating with said fuel manifold by means of a pair of exterior conduits extending from the manifold directly to opposite ends of said passage in the cylinder head, each said exterior conduit extending exteriorly of the valve covers to preclude contamination of engine lubricant with fuel that may leak from the connections between exterior conduits and the passages in the cylinder head.