16900-ZV5-901 Honda JOINT ASSY., FUEL (Honda Code 4731238).

Governor Operation Overview
This engine utilizes a separated fuel injection pump in combination with a multifunction mechanical governor. This governor also utilizes a torque limiting mechanism to control the maximum peak torque. This mechanism maintains a constant level under varying loads, and provides stable idling and regulates maximum engine speed This engine uses a mechanical governor that controls the fuel injection rate at all engine speed ranges. A balance between the centrifugal force of the flyweights and spring tension is used in order to control the fuel injection rate at all rpm.The governor shaft that monitors engine speed is independent of the injection pump shaft and rotates at twice the speed of conventional types. This provides better response to load variance and delivering greater engine output.Governor Operation At Engine Start-Up
Illustration 1 g02893498
(1) Start spring
(2) Flyweights The stop solenoid is powered in order to release the stop lever. Low tension of start spring (1) permits the control rack to move to the starting position, which supplies the proper amount of fuel that is required to start the engine.Governor Operation At Idle
Illustration 2 g02893657
(1) Start spring
(2) Flyweights
(3) Second fork lever
(4) Speed control lever
(5) Spring pin
(6) First fork lever
(7) Governor spring When the speed control lever (4) is rotated in the clockwise direction, the increased tension of the governor spring (7) pulls second fork lever (3). Second fork lever (3) is pulled the torque lever pin and first fork lever (6) are moved in direction toward the front of the fuel pump in order to restrain the flyweight. Governor Operation At Rated Speed with Full Load and Overload
Illustration 3 g02878757
(8) No-load maximum rotation
(9) Output limiting bolt
(10) Torque limiting bolt As the speed control lever is changed from the middle speed range to the high speed range, the governor spring tension increases in order to compress the torque spring. This moves the first fork lever in the direction toward the front of the fuel pump.The second fork lever moves until the lever reaches the output limiting bolt (9) to keep rated rotation and rated output. When the engine is overloaded, the engine rotating speed decreases and the centrifugal force of the flyweight decreases. This moves the first fork lever in the direction toward the front of the fuel pump.The control rack moves in the direction that increases the fuel supply in order to increase output. The control rack is balanced with the centrifugal force of the flyweights to produce low-speed output.Governor Operation At Engine Stop
Illustration 4 g02894136
(11) Solenoid
(12) Stop lever shaft Stop solenoid (11) is switched to the off position, the spring tension of the solenoid is released. This causes the rod to extrude, and stop lever (12) moves the control rack in direction toward the front of the fuel pump, which stops the engine.Two-Stage Fuel Injector
Illustration 5 g03331936
(13) Edge filter
(14) Nozzle body holder
(15) First stage injection pressure adjusting shim
(16) First spring
(17) Pressure pin
(18) Spring seat
(19) Second stage injection pressure adjusting shim
(20) Second spring
(21) Pre-lift adjusting spring seat
(22) Chip packing
(23) Maximum lift adjusting washer
(24) Retaining nut
(25) Nozzle The two-spring holder limits needle valve lift at initial valve opening in order to throttle the injection quantity. Main injection occurs when the in-line pressure has increased sufficiently to move the needle valve through the full life of the injector cycle. The new two stage fuel injectors include the following improvements:
Improved engine stability at low and intermediate speeds
Decreased engine hunting and surging
Decreased noise at idle
Decreased idling speed due to improved engine stability
Stabilized fuel injection characteristics from the fuel injection pump and nozzleFirst Opening Pressure
The force of the high-pressure fuel that is delivered by the injection pump forces the needle valve in the upward direction. The force overcomes the set force of the first spring. The needle valve of the nozzle forces the pushrod up and the needle valve opens.Second Opening Pressure
After the pushrod is lifted through the pre-lift position the second pushrod is contacted. The set force of the second spring acts on the second pushrod. The combined forces of the first and second spring acts on the needle valve. The needle valve will not lift until the forces are overcome.When the high-pressure fuel overcomes the combined spring force, the needle valve is again lifted, and main injection can begin. Injection Pump with Fine Spill Port (FSP) Mechanism
Illustration 6 g03331938
View of FSP mechanism
(A) FSP stroke
(26) Barrel
(27) Plunger chamber
(28) Plunger
(29) Main port
(30) Fine spill port The fuel injection pump with FSP. The speed timer function delays the injection timing at low idle in order to reduce NOx and operating noise. The injection rate control function decreases the initial inj