Abstract: An outboard motor has a lubricant pump driven by an engine. The lubrication pump circulates lubricant to moving components of the engine through at least one lubricant passage. A pressure sensor is provided along the lubricant passage. The pressure sensor outputs a signal to an evaluator to determine whether a low pressure situation indicative of a malfunction has occurred. An alarm is activated based upon the determination of a malfunction. Activation of the alarm may occur if the engine is not warmed-up, if the engine is operating at a steady speed or encountering slow speed changes or has encountered a rapid speed change for a predetermined period of time. In this manner, false alarms related to pressure variations within the lubricant system may be reduced.

Abstract: An outboard motor has a lubricant pump driven by an engine. The lubrication pump circulates lubricant to moving components of the engine through at least one lubricant passage. A pressure sensor is provided along the lubricant passage. The pressure sensor outputs a signal to an evaluator to determine whether a low pressure situation indicative of a malfunction has occurred. An alarm is activated based upon the determination of a malfunction. Activation of the alarm may occur if the engine is not warmed-up, if the engine is operating at a steady speed or encountering slow speed changes or has encountered a rapid speed change for a predetermined period of time. In this manner, false alarms related to pressure variations within the lubricant system may be reduced.

Abstract: An improved overheat detection system for an engine having at least one coolant jacket which is drained of coolant when the engine is not running. The coolant jacket has an inlet portion into which the coolant is supplied and an outlet portion from which the coolant is discharged during the engine is running. In one feature of this invention, the overheat detection system has a sensor for sensing a temperature associated with the coolant jacket at an aft part of the coolant jacket including the outlet portion. In another feature of this invention, the overheat detection system has at least two sensors, one is positioned at a fore part of the coolant jacket including the inlet portion and another is positioned downstream of the former sensor, and both sensors for sensing each temperature associated with the coolant jacket. The overheat detection system is arranged to output an overheat signal in the event the temperature sensed by the sensor or at least one of the sensors is above a predetermined temperature.

Abstract: The present invention is an ignition control system controlling ignition firing timing of an ignition element associated with an engine having an output shaft powering a water propulsion device, an intake system including a throttle valve, and a sensor providing an output signal corresponding to each revolution of the output shaft. The ignition control system calculates a base ignition firing timing from a time between successive previous output signals, determines if a condition of engine acceleration or deceleration exists from a rate of change in the throttle valve position and modifies the basic ignition firing timing based on a condition of engine acceleration or deceleration.

Abstract: A control for a marine propulsion unit including a water propulsion device powered by an engine through a transmission. The transmission has forward, neutral and reverse positions. The engine has at least one combustion chamber, an air and fuel supply system, and at least one ignition element corresponding to the combustion chamber for igniting an air and fuel mixture supplied to the combustion chamber. The control is arranged to delay the firing of the ignition element when the engine is idling from a normal firing timing, and arranged to advance the firing of the ignition element if the engine speed rapidly reduces and the position of the transmission is changed from neutral to reverse or forward.

Abstract: The present invention is an ignition control system controlling ignition firing timing of an ignition element associated with an engine. The engine includes an output shaft powering a water propulsion device, an intake system including a throttle valve, and a sensor providing an output signal corresponding to each revolution of the output shaft. The ignition control system calculates a base ignition firing timing from a time between successive previous output signals, and determines if a low-temperature idle condition of engine exists from the sensed throttle angle and coolant temperature. If such condition exists, the ignition control system also determines a compensation value to compensate ignition timing to either the advance or delay side to generally match a target engine speed for a given coolant temperature, and modifies the basic ignition firing timing by the compensation value.

Abstract: A marine propulsion control that permits the use of transmission braking for a watercraft without the likelihood of engine stalling by increasing engine speed during this condition. Nevertheless normal idle speeds can be maintained when running in neutral. This is accomplished with a single lever control.

Abstract: The present invention is an ignition control system for an engine having an ignition system. The ignition control system is arranged to determine if a speed of the engine is decreasing at greater than a predetermined rate, and if so, to initiate an ignition timing compensation mode in which target engine speeds during the time of deceleration are set. These target engine speeds are compared to the actual engine speed and a firing timing of the ignition is advanced if the actual engine speed is less than the target speed and the firing timing of the ignition system is delayed if the actual engine speed exceeds the target speed.

Abstract: The present invention is an overheat detection system for an engine having at least one cooling jacket which is drained of coolant when the engine stops running. The detection system includes a sensor for sensing a temperature associated with the cooling jacket. The detection system is arranged to output an overheat signal in the event the temperature sensed by the sensor is above a predetermined temperature except within a predetermined time after the engine has been started.

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 marine propulsion system and particularly an outboard motor wherein the outboard motor is provided with a control for preventing engine damage in response to an abnormal condition by reducing the speed of the engine through disabling certain cylinders. The cylinders disabled are chosen on the vertical position of the cylinder in the engine so as to provide improved running and avoid undesirable results. In addition, the disabling of the cylinders is precluded until the abnormal condition has existed more than a predetermined time period upon initial start-up so as to permit unencumbered normal warm up of the engine.

Abstract: An insulator supports a plurality of charge formers on the end of an intake manifold. The insulator, made in part of elastic material, thermally decouples the charge formers from the engine to reduce conduction of engine heat to the charge formers. Expansion of the intake manifold due to heat deforms the insulator, without substantially moving the charge formers so as not to deform a linkage which interconnects the charge formers.

Abstract: An engine choke actuation system controls both the opening degree of the choke and throttle valves of a plurality of charge formers during all phases of engine warmup. The engine choke actuation system includes a first device which acts to close the choke valve at the time of engine starting. A second device restricts a degree of closure of the choke valve by the first device depending upon the temperature of the engine at the time of engine starting. The second device also controls the opening degree of the choke valves after engine starting, increasing the opening degree of the choke valve with increasing engine temperature. In addition, the second device controls the fast idle angle of the throttle valves during engine warmup, decreasing the fast idle angle of the throttle valves as the engine temperature increases.

Abstract: A throttle linkage system for synchronizing the movement between a plurality of throttle valves journaled in throttle bodies affixed to a common member that includes a link that has the same coefficient of thermal expansion as the member to which the throttle bodies are connected so as to avoid synchronization problems due to different thermal expansions. In addition, the linkage system is such that it accommodates manufacturing variations from the more remotely positioned throttle valves by providing a structure for permitting relative movement.

Abstract: A mounting arrangement for an accelerator pump and a choke actuation mechanism, which are used in conjunction with a plurality of charge formers, minimizes the girth of the engine while making these components more accessible and easing assembly. An actuator and a choke solenoid of the choke actuation system are mounted proximate to one another and partially between adjacent induction pipes of an induction system. This position allows these components to be located on an exterior side of the induction system without interfering with the protective cowling of the motor. The accelerator pump is mounted at the end of a series of charge formers, proximate to a throttle linkage which controls throttling devices of the charge formers. This position of the accelerator pump eases the installation of this component without increasing the girth of the engine.

Abstract: A mounting arrangement for an accelerator pump and a choke actuation mechanism, which are used in conjunction with a plurality of charge formers, minimizes the girth of the engine while making these components more accessible and easing assembly. An actuator and a choke solenoid of the choke actuation system are mounted proximate to one another and partially between adjacent induction pipes of an induction system. This position allows these components to be located on an exterior side of the induction system without interfering with the protective cowling of the motor. The accelerator pump is mounted at the end of a series of charge formers, proximate to a throttle linkage which controls throttling devices of the charge formers. This position of the accelerator pump eases the installation of this component without increasing the girth of the engine.

Abstract: A linkage system interconnects a plurality of throttle shafts, while minimizing the effects of thermal expansion in the linkage on the throttle shafts. The linkage includes a plurality of linkage rods which interconnect a plurality of throttle levers attached to the throttle shafts. At least a first and a second linkage rod are connected to a first lever in a manner in which thermal expansion of the first linkage rod applies a force to the first lever which is equal but opposite to a force applied to the first lever due to thermal expansion of the second linkage rod.

Abstract: A ventilation system is provided for an engine crankcase of a marine outboard motor to distribute blow-by gas generally equally to each cylinder while minimizing the size of an intake silencer of the system. The intake silencer includes a first expansion chamber into which the blow-by gas is introduced from a blow-by gas camber attached to the cylinder head. The blow-by gas diffuses and mixes with ambient air which is drawn into the first expansion chamber through an inlet port of the induction system. The air/blow-by gas mixture is then drawn into a second expansion chamber where it distributes generally evenly before induction into a charge forming device.

Abstract: A water cooled outboard motor engine including several embodiments of ensuring that the fuel pumped by the fuel pump is not heated excessively. The embodiments include either cooling jackets through which engine coolant is circulated for cooling the fuel, or the insulation of the pumping element driven by the engine from the fuel.

Abstract: Two embodiments of cold starting and cold running enrichment devices for internal combustion engines, each of which provide an amount of fuel through a first circuit under the control of a first control valve during cold cranking for cold starting enrichment and a second fuel circuit having a second control valve for supplying fuel to the engine for cold running enrichment. In this way, adequate amounts of fuel are supplied under all circumstances.