Abstract: A fuel pump mounting arrangement for a fuel system of an engine powering a watercraft is disclosed. The watercraft has a hull defining an engine compartment and having a lower surface, a water propulsion device, and an internal combustion engine positioned in the engine compartment and supported by the lower surface of the hull. The engine has an output shaft arranged to drive the water propulsion device. The watercraft has an air intake system for supplying the engine with air for use in a combustion process, the intake system including at least one air intake through the hull leading into the engine compartment, the watercraft including a fuel supply system for supplying fuel from a fuel supply to the engine for combustion, the fuel supply system including a fuel pump delivering fuel from the fuel supply to said engine, the fuel pump positioned to avoid exposure to water which enters the engine compartment through the hull.

Abstract: A number of embodiments of personal watercraft having catalytic exhaust systems for treating and purifying the exhaust gases. In all of the embodiments, the catalyst is positioned and disposed so as to be protected from water. In addition, arrangements are provided for cooling the catalyst, for circulating ventilating air across it, for isolating it from other components such as the fuel tank, and for permitting its flushing with fresh water after operating in a salt water environment.

Abstract: A mounting arrangement for a throttle position sensor associated with a throttle valve is disclosed. The throttle valve is positioned within an intake pipe of an intake system of an engine which is positioned in an engine compartment defined by a hull of a watercraft. An output shaft of the engine is arranged to drive a water propulsion device of the watercraft. The intake pipe extends from the engine and is arranged to route air to a combustion chamber of the engine. The throttle position sensor is mounted so as to be shielded by the intake pipe from a source of water within the engine compartment, such as an outlet of an intake duct leading through the hull of the watercraft.

Abstract: A personal watercraft includes a catalytic exhaust system in order to reduce discharge of pollutants. A catalyzer of the exhaust system is located within an expansion chamber. The expansion chamber, as well as the internal combustion engine of the personal watercraft, are enclosed within a hull. The watercraft hull desirably includes an access opening located near the catalyzer. The access opening is of a size sufficient to allow at least the catalyzer to be removed from the hull of the personal watercraft for servicing or cleaning.

Abstract: An oil supply system for a watercraft is disclosed. The watercraft has a water propulsion device and a hull defining an engine compartment, an internal combustion engine positioned in the engine compartment and having an output shaft arranged to power the water propulsion device. The engine has at least one combustion chamber and an intake and exhaust path including an air intake system through which air is provided to the combustion chamber(s) and an exhaust system for routing products of combustion from the combustion chamber(s) to a discharge, the exhaust system including a water lock between the discharge and the engine. The engine also includes a fuel supply system supplying fuel to the combustion chamber(s) for combustion with the air. The oil supply system is arranged to introduce lubricant to the engine along the intake and exhaust path upstream of the water lock.

Abstract: An oil supply system for a watercraft is disclosed. The watercraft has a water propulsion device and a hull defining an engine compartment, an internal combustion engine positioned in the engine compartment and having an output shaft arranged to power the water propulsion device. The engine has at least one combustion chamber and an intake and exhaust path including an air intake system through which air is provided to the combustion chamber(s) and an exhaust system for routing products of combustion from the combustion chamber(s) to a discharge, the exhaust system including a water lock between the discharge and the engine. The engine also includes a fuel supply system supplying fuel to the combustion chamber(s) for combustion with the air. The oil supply system is arranged to introduce lubricant to the engine along the intake and exhaust path upstream of the water lock.

Abstract: An improved exhaust probe arrangement within an exhaust system of a small watercraft increases the accuracy of the probe's readings. The aperture is located upstream of a point where cooling water is introduced into the exhaust system for silencing purposes. As a result, the ingress and egress of exhaust gases flow into and out of the aperture is generally unimpeded by the cooling water. The tendency of water to enter and clog the aperture is also reduced. The precision of the exhaust probe measurements consequently is greatly increased.

Abstract: A mounting arrangement for a throttle position sensor associated with a throttle valve is disclosed. The throttle valve is positioned within an intake pipe of an intake system of an engine which is positioned in an engine compartment defined by a hull of a watercraft. An output shaft of the engine is arranged to drive a water propulsion device of the watercraft. The intake pipe extends from the engine and is arranged to route air to a combustion chamber of the engine. The throttle position sensor is mounted so as to be shielded by the intake pipe from heat generated by the engine and radiated therefrom and from an exhaust system associated therewith.

Abstract: An improved fuel delivery and injection system for a small watercraft engine reduces the heat effects within an enclosed engine compartment upon various components of the engine and upon the fuel within the fuel system. The fuel system integrates a fuel pump within a fuel tank at a location which minimizes the effects of watercraft leaning. The inlet of the fuel pump desirably corresponds, in the lateral direction, with a position of an inlet to the jet pump unit. In this position, the pump is less likely to draw air as the watercraft maneuvers. The fuel lines also are arranged within the engine to minimize the effect of engine heat produced by the exhaust system on the fuel delivery lines. The arrangement of the fuel pump and fuel delivery lines consequently improves the consistency of the fuel/air ratio within the fuel charge produced by the engine as less air and vapor delivered to the fuel injectors.

Abstract: An arrangement for at least one air temperature sensor for measuring the temperature of air entering the combustion chamber of a fuel injected engine powering a water propulsion device of a watercraft is disclosed. The watercraft has a hull defining an engine compartment in which the engine is positioned. The engine has a body defining at least one combustion chamber and an output shaft arranged to drive the water propulsion device. At least one air duct provides air through the hull into the engine compartment, the duct leading from the hull to an outlet in the engine compartment. The engine has an intake system for providing air to the combustion chamber and a fuel system for providing fuel to the combustion chamber, the fuel system including at least one fuel injector. The arrangement of the air temperature sensor(s) reduces or limits each sensor's exposure to water.

Abstract: Two embodiments of two-cycle V-type crankcase compression internal combustion engines for powering a jet propelled watercraft. In each embodiment, the pistons of the cylinder banks each drive their own crankshafts which are geared by a transmission to an output shaft. The exhaust system for the engine is disposed on the outside of the cylinder banks and includes an expansion chamber and a portion of the exhaust system that passes over the engine. The induction system for the engine is positioned in the valley between the cylinder banks.

Abstract: An improved catalytic exhaust system for a watercraft provides two stage treatment of exhaust gases before expulsion from the watercraft. The catalytic exhaust system also is configured to minimize the restriction the catalysts pose to exhaust gas flow through the exhaust system so as to reduce engine back pressure and improve engine performance. A catalytic device of the exhaust system includes a pre catalyst and a main catalyst positioned downstream from the pre catalyst. The pre catalyst can take the from of a catalytic material coating along a portion of the exhaust flow path and the main catalyst can be a catalyst bed. The exhaust gas flow path through the exhaust system also smoothly tapers into and out of the main catalyst so as to reduce the degree of flow resistance through the main catalyst.

Abstract: A watercraft engine control system for controlling the temperature in the exhaust system to protect against potentially dangerous situations. If the exhaust temperature is sensed to be unduly high, a protective action is initiated. This protective action reduced in the flow of unburned fuel to the exhaust system either stopping of the engine or reducing its speed below idle. The protection action may be initiated either immediately or if the situation occurs for more than a predetermined time period.

Abstract: An exhaust pipe cooling system is provided for a small watercraft, such as a personal watercraft, to regulate the temperature of a catalyzer of an associated exhaust system. The cooling system supplies fresh water to a water jacket which surrounds the catalyzer in a manner independent of an engine cooling system. A control valve also can regulate the flow rate of water through the cooling system to adjust the temperature of the catalyzer to fall within a desired range of operating temperatures.

Abstract: An oil supply system for a watercraft which is powered by an internal combustion engine driving a water propulsion device is disclosed. The system delivers oil to the engine in accordance with a first rate of increase as engine speed increases in a first low engine speed range, and in accordance with a second higher rate of increase as engine speed increases in a second engine speed range higher than the first engine speed range. The lower rate of oil delivery in the first engine speed range is selected to prevent fouling of a catalyst of the engine.

Abstract: A two-cycle internal combustion engine for a watercraft that includes a cylinder block having a cylinder bore, a piston reciprocating in the cylinder bore and an exhaust port formed in the cylinder block. An exhaust path extends from the cylinder bore for exhausting combustion products from the cylinder bore. An exhaust control valve cooperates with the exhaust port and is movable between at least a first position for advancing the closing of the exhaust port so as to increase the compression ratio in the engine and a second position for delaying the closing of the exhaust port so as to decrease the compression ratio in the engine. Means for controlling the exhaust control valve between the first and second position are provided and are controlled in response to a watercraft condition.

Abstract: A lubricant supply system is provided for the induction system of a marine propulsion engine. The lubricant supply system delivers lubricant to the a flow controlling valve in the induction system upon shutting down of the engine and can be operated manually at the discretion of a user. The lubricant serves to reduce the likelihood of post-operation corrosion of the valve, particularly at the sliding support surfaces of the valve and also provides lubricant from start-up operation.

Abstract: A number of embodiments of a personal watercraft are disclosed which have a catalytic exhaust system for treating and purifying exhaust gases. In all of the embodiments, the catalyst is positioned and disposed so as to be protected from water. In addition, arrangements are provided for cooling the catalyst, for discharging at least a portion of coolant upstream of the catalyst, for circulating ventilating air across it, for isolating it from other components such as the fuel tank, and for permitting its flushing with fresh water after operating in a salt water environment.

Abstract: A number of embodiments of engine induction system configurations for adapting four-cycle, multi-cylinder engines for use in small, personal watercraft. This is accomplished by canting the engine at an angle to a vertically extending plane and positioning the induction system on the upper portion of the cylinder head. Various configurations of manifold and carburetor locations are disclosed so as to achieve this purpose.

Abstract: A number of embodiments of personal watercraft having catalytic exhaust systems for treating and purifying the exhaust gases. In all of the embodiments, the catalyst is positioned and disposed so as to be protected from water. In addition, arrangements are provided for cooling the catalyst, for circulating ventilating air across it, for isolating it from other components such as the fuel tank, and for permitting its flushing with fresh water after operating in a salt water environment.