Duel fuel pump and oil-fuel mixing valve system

摘要

A marine propulsion system (2) with an outboard engine (4) has an oil-fuel mixing valve (16) within the engine cowl (6). A first crankcase pressure driven fuel pump (20) delivers fuel from a remote fuel tank (14) to the mixing valve, and a second crankcase pressure driven fuel pump (22) delivers mixed oil-fuel from the mixing valve to the engine. The arrangement provides adequate fuel pressure to overcome the added pressure drop across a reduced size mixing valve, all fitting within the engine cowl. The crankcase pressure pulses to the fuel pumps are 180 DEG out of phase such that when the first pump is pushing pressurized fuel to the inlet of the mixing valve, the second pump is pulling suctioned oil-fuel from the outlet of the mixing valve, to increase fuel pressure differential and enhance operation of the mixing valve.