Abstract: A fuel supply system for a marine propulsion system having an electronically controlled fuel injection system eliminates the need for a vapor separator. The system pumps an excessive amount of fuel through a plumbed fuel supply loop and cools recirculated fuel to cool all the components in the plumbed fuel supply loop, i.e. a continuous duty, constant displacement fuel pump; a pressure regulator; and a water separating fuel filter. Recirculated fuel flows from the pressure regulator to the water separating fuel filter as does make-up fuel from a fuel tank. The fuel stream from the water separating fuel filter flows to the low-pressure side of the fuel pump, which pumps the fuel through the plumb fuel supply loop. A fuel injection portion of the fuel flows to the engine for combustion, while the remaining portion of the fuel is recirculated. The recirculated portion of the fuel is cooled, preferably using a water-cooled heat exchanger.

Abstract: A heat exchanger assembly is provided for a marine propulsion system having a closed loop cooling system. The heat exchanger body encloses a series of tubes carrying sea water which removes heat from the engine coolant. The heat exchanger includes an integrally connected top tank. A single venting orifice is provided into the top tank from the heat exchanger body. A heat exchanger coolant outlet is in direct fluid communication with both a system bypass and the coolant in the top tank. An auxiliary inlet for coolant from the top tank is located in the heat exchanger coolant outlet downstream of the bypass inlet, thereby promoting the ability of the system to draw coolant through the top tank rather than the bypass. The invention minimizes cavitation and reduces the creation of negative pressure at the circulating pump.