Abstract: An improvement in an injection internal combustion engine having at least one fuel injection pump therein which is connected to the fuel supply tank through a suction conduit having a check valve connected in circuit therewith. Fuel which is not injected into the internal combustion engine is returned to the supply tank through another check valve located in a separate conduit from the suction conduit. The check valve in the separate conduit, when it is in its seated position, permits a small flow of fuel between the injection pump and the separate conduit.