Abstract: A multiple-cylinder engine for a planing water vehicle includes an operation control device which changes the number of deactivated cylinders step by step in response to an engine speed when the engine speed exceeds a preset speed. The operation control device can have a plurality of cylinder deactivation order maps used for instructing an increment order of cylinders which are deactivated step by step when the engine speed exceeds the preset speed. The operation control device can exchange one of the cylinder deactivation order maps which is currently used for another one of the maps in accordance with an operation state of the engine.

Abstract: An operation control system for a small boat can include a mode selection module configured to allow a driver to select between a plurality of driving modes including at least a normal operation mode, in which the boat cruises at a speed in response to the displacement of an acceleration controller, and a low-speed setting mode, in which the boat cruises at a preset low speed when a low-speed setting controller is operated; in which the mode selection module permits the driving mode to switch to the low-speed setting mode if the displacement of the acceleration controller is zero, or small or close to zero or is in or substantially at an idle position.

Abstract: A throttle opening controller for one embodiment of a small planing boat includes: a throttle valve for changing the degree of opening in response to displacement of a throttle lever; a remaining fuel amount detector; a fuel consumption calculating means; and a throttle opening limiting means. In one embodiment, when a remaining fuel amount detected by the remaining fuel amount detector is equal to or below a preset value L1, the fuel consumption calculating means starts calculating total fuel injection amount. When a value, obtained by subtracting the total fuel injection amount from the preset value L1, is equal to or below a threshold L0, the throttle opening limiting means determines the degree of opening of the throttle valve based on an opening rate (k). An internal space of a fuel tank can be divided using a vertical partition into plural chambers. In addition, a knock sensor can be provided for an engine.

Abstract: A jet-propelled watercraft can include an engine output control system that adjusts the output of the engine based on a steering force and the engine speed. The control system can also be configured to detect abnormalities in the steering force sensor and to prohibit the increase engine output control when an abnormality is detected.

Abstract: An operating state determining device can determine whether or not an engine is in a certain operating state. A mode setting device can disable mode setting into a speed setting mode if a certain operating state of the engine has been determined, and can enable mode setting into the speed setting mode if the engine is not in the operating state.

Abstract: An engine control device can be capable of suppressing a rise in engine speed at starting. The engine speed can be detected by a speed sensor and a determination can be made whether the engine speed has changed from a starting mode to a normal mode. If the engine speed has changed from a starting mode to a normal mode, the difference between the engine speed and a predetermined target engine speed is calculated, and the ignition timing is controlled based on the calculated difference. The control of ignition timing can be performed when the detected value of the rotational sensor is larger than the target engine speed.

Abstract: An engine control device can include a throttle valve for adjusting an amount of air supplied to an engine, operation amount detecting sensors for detecting an operation amount of a throttle lever, a motor for driving the throttle valve between open and closed positions according to detection values of the operation amount detecting sensor 21a or the like, and throttle opening detecting sensors for detecting an opening of the throttle valve is provided with a limp-home mechanism for keeping the throttle valve in a mechanically neutral position when an abnormality occurs. When the throttle valve is in the mechanically neutral position, an ignition timing control can be switched in a stepwise manner over a predetermined time period from a regular ignition timing control to a limp-home ignition timing control.

Abstract: An operation control system for a planing boat can include a mode selection module configured to allow a driver to select a driving mode of either one of a normal operation mode, in which the boat cruises at a speed in response to the displacement of an acceleration controller, and a speed-fixing mode, in which the boat cruises at a fixed speed at a level when a speed-fixing controller is operated. The system can also include a planing condition determination module configured to determine whether a hull is at the stage of planing, in which the mode selection module is configured to prohibit the driving mode from switching to the speed-fixing mode if the planing condition determination module determines that the hull is not at the stage of planning. The mode selection module can also be configured to permit the driving mode to switch to the speed-fixing mode if the planing condition determination module determines that the hull is at the stage of planing.

Abstract: A throttle opening controller for one embodiment of a small planing boat includes: a throttle valve for changing the degree of opening in response to displacement of a throttle lever; a remaining fuel amount detector; a fuel consumption calculating means; and a throttle opening limiting means. In one embodiment, when a remaining fuel amount detected by the remaining fuel amount detector is equal to or below a preset value L1, the fuel consumption calculating means starts calculating total fuel injection amount. When a value, obtained by subtracting the total fuel injection amount from the preset value L1, is equal to or below a threshold L0, the throttle opening limiting means determines the degree of opening of the throttle valve based on an opening rate (k). An internal space of a fuel tank can be divided using a vertical partition into plural chambers. In addition, a knock sensor can be provided for an engine.

Abstract: An operation control system for a planing boat can include a mode selection module configured to allow a driver to select a driving mode of either one of a normal operation mode, in which the boat cruises at a speed in response to the displacement of an acceleration controller, and a speed-fixing mode, in which the boat cruises at a fixed speed at a level when a speed-fixing controller is operated. The system can also include a planing condition determination module configured to determine whether a hull is at the stage of planing, in which the mode selection module is configured to prohibit the driving mode from switching to the speed-fixing mode if the planing condition determination module determines that the hull is not at the stage of planning. The mode selection module can also be configured to permit the driving mode to switch to the speed-fixing mode if the planing condition determination module determines that the hull is at the stage of planing.

Abstract: An engine control device can include a throttle valve for adjusting an amount of air supplied to an engine, operation amount detecting sensors for detecting an operation amount of a throttle lever, a motor for driving the throttle valve between open and closed positions according to detection values of the operation amount detecting sensor 21a or the like, and throttle opening detecting sensors for detecting an opening of the throttle valve is provided with a limp-home mechanism for keeping the throttle valve in a mechanically neutral position when an abnormality occurs. When the throttle valve is in the mechanically neutral position, an ignition timing control can be switched in a stepwise manner over a predetermined time period from a regular ignition timing control to a limp-home ignition timing control.

Abstract: A watercraft has an engine that is controlled to provide a comfortable and natural operational feeling during an off-throttle steering environment. The engine is controlled by detecting engine speed, using the detected engine speed to establish an accurate watercraft speed, and detecting an operator steering torque and operator engine torque request. An operational characteristic of the engine is adjusted to increase the engine output by a predetermined amount after a predetermined steering torque is measured and the watercraft is determined to be in a predetermined deceleration phase. The operational characteristic can be an increase in airflow to the engine.

Abstract: A personal watercraft includes a hull and an engine. The engine has an air intake system through which air is delivered to combustion chambers of the engine. An overturn switch detects overturn of the hull. A control device stops an operation of the engine based upon an output of the overturn switch. A throttle valve is disposed in the air intake system to be actuated by a throttle valve actuator. The control device controls the blocks the intake system based upon the output of the overturn switch to inhibit water from moving toward the combustion chambers. The control device allows the engine to be restarted during a preset period of time after stopping the engine operation.

Abstract: An engine control device can include a throttle valve for adjusting an amount of air supplied to an engine, operation amount detecting sensors for detecting an operation amount of a throttle lever, a motor for driving the throttle valve between open and closed positions according to detection values of the operation amount detecting sensor 21a or the like, and throttle opening detecting sensors for detecting an opening of the throttle valve is provided with a limp-home mechanism for keeping the throttle valve in a mechanically neutral position when an abnormality occurs. When the throttle valve is in the mechanically neutral position, an ignition timing control can be switched in a stepwise manner over a predetermined time period from a regular ignition timing control to a limp-home ignition timing control.

Abstract: An engine control device can include a throttle valve for adjusting an amount of air supplied to an engine, operation amount detecting sensors for detecting an operation amount of a throttle lever, a motor for driving the throttle valve between open and closed positions according to detection values of the operation amount detecting sensor 21a or the like, and throttle opening detecting sensors for detecting an opening of the throttle valve is provided with a limp-home mechanism for keeping the throttle valve in a mechanically neutral position when an abnormality occurs. When the throttle valve is in the mechanically neutral position, an ignition timing control can be switched in a stepwise manner over a predetermined time period from a regular ignition timing control to a limp-home ignition timing control.

Abstract: An operation control system for a small boat can include a mode selection module configured to allow a driver to select between a plurality of driving modes including at least a normal operation mode, in which the boat cruises at a speed in response to the displacement of an acceleration controller, and a low-speed setting mode, in which the boat cruises at a preset low speed when a low-speed setting controller is operated; in which the mode selection module permits the driving mode to switch to the low-speed setting mode if the displacement of the acceleration controller is zero, or small or close to zero or is in or substantially at an idle position.

Abstract: An operation control system for a planing boat can include a mode selection module configured to allow a driver to select a driving mode of either one of a nonnal operation mode, in which the boat cruises at a speed in response to the displacement of an acceleration controller, and a speed-fixing mode, in which the boat cruises at a fixed speed at a level when a speed-fixing controller is operated. The system can also include a planing condition determination module configured to determine whether a hull is at the stage of planing, in which the mode selection module is configured to prohibit the driving mode from switching to the speed-fixing mode if the planing condition determination module determines that the hull is not at the stage of planning. The mode selection module can also be configured to permit the driving mode to switch to the speed-fixing mode if the planing condition determination module determines that the hull is at the stage of planing.

Abstract: A personal watercraft has a jet pump propulsion device. An engine powers the propulsion device and a control device controls engine speed. A steering mechanism steers a thrust direction of the propulsion device. An engine load sensor or an engine speed sensor senses an engine load or an engine speed, respectively. A steering position sensor senses an angular position of the steering mechanism. The control device decreases engine speed when the engine load or the engine speed is greater than a preset engine load or the engine speed, respectively, and the angular position of the steering mechanism is greater than a preset angular position.

Abstract: An engine control device can be capable of suppressing a rise in engine speed at starting. The engine speed can be detected by a speed sensor and a determination can be made whether the engine speed has changed from a starting mode to a normal mode. If the engine speed has changed from a starting mode to a normal mode, the difference between the engine speed and a predetermined target engine speed is calculated, and the ignition timing is controlled based on the calculated difference. The control of ignition timing can be performed when the detected value of the rotational sensor is larger than the target engine speed.

Abstract: A jet-propelled watercraft can include an engine output control system that adjusts the output of the engine based on a steering force and the engine speed. The control system can also be configured to detect abnormalities in the steering force sensor and to prohibit the increase engine output control when an abnormality is detected.