Abstract: An exhaust system of a marine propulsion device is provided with a bifurcated cooling passage in its elbow structure in order to limit the effect of cold water being disposed in thermal communication with exhaust gas passing through the elbow structure. This thermal communication between a stream of cold water and exhaust gas passing through the elbow structure is minimized in order to reduce the likelihood that water vapor will condense out of the stream of exhaust gas as it passes through the elbow structure. An obstruction, or water dam, is used to bifurcate the coolant chamber within the elbow structure while allowing passage of coolant through the obstruction.

Abstract: An engine starting fuel enriching system provides a valve that is located downstream of an air feed conduit that is connected in fluid communication with a first fuel conduit. The fuel conduit is connected between a fuel reservoir and the valve. When the valve is in a closed position, both fuel and air are inhibited from flowing in a direction from the fuel reservoir and the air feed conduit toward the air intake manifold of the engine. A heater circuit is used to activate a valve actuator as a function of the temperature of the engine.

Abstract: A block of material is attached to a surface of a throttle plate in a throttle body assembly for the purpose of reducing sound emanating from the throttle plate region. The block of material has a first edge attached proximate to a perimeter of the throttle plate and second edge disposed more proximate the pivot axis of the throttle plate. The block of material is formed to have a central region and two distal regions. The distal regions are hyperbolic in shape and taper toward the outer edges of the block of material. Two holes are formed through the block of material.

Abstract: An exhaust system for a marine engine provides individual exhaust gas conduits that are maintained separately from water conduits until the individual exhaust gas conduits can be combined within a common exhaust gas conduit. This combination of exhaust gas streams allows the amplitude of negative pressure pulses to be damped, by combination with each other, prior to the mixing of cooling water with the exhaust gas streams. Later, the combined exhaust gas stream can be mixed with a combined water stream.

Abstract: A marine propulsion system is provided with a liquid detector located within a cooling passage of the cooling system of an engine. Conductivity sensors, or other types of liquid sensors, provide signals representative of the absence or presence of water at particular locations within the cooling system. The signals are used to energize and de-energize various annunciators on a display panel to inform the operator of a marine vessel of the status of a draining procedure. When all of the annunciators properly indicate the absence of water within strategic locations of the cooling system, the marine vessel operator can be assured that the draining procedure has been effectively completed.

Abstract: An exhaust system is provided with a structure that separates water from an exhaust stream and also attenuates the noise of the exhaust system. Water laden exhaust is directed from an inlet conduit through a perforated surface to precipitate water from the water laden exhaust stream. After the water is precipitated out of the exhaust stream, the gaseous portion of the exhaust stream continues from the inlet chamber 24 to an outlet chamber 28 and exits from the housing structure by passing through a first outlet conduit. The precipitated water passes from the housing structure through a second outlet conduit.

Abstract: An exhaust pressure pulsation control apparatus for a marine propulsion system has a front ring and a reflector disk located downstream of the front ring. There is a space between the front ring and the reflector disk that is sufficiently large so that the mixture of water and water cooled exhaust passing through the apparatus does not have a significant pressure drop. The apparatus attenuates pressure pulsations in the exhaust system, thereby significantly reducing water ingestion through the exhaust system into the engine. The apparatus does not create significant exhaust back pressure, and typically increases engine maximum power output.