Yamaha WaveRunner FX140 Service Manual page 28

Fully closed cutoff
If engine speed exceeds 6,000 r/min and the throttle angle is near fully closed (below 2.4°), fuel
injection is stopped.
Engine stop cutoff
• If the emergency stop switch is on.
• If the slant detection switch is on (i.e., engine speed is less than 3,000 r/min).
• When the engine is restarted, and if engine speed is less than 1,000 r/min and the throttle is
open more than 10°, ignition and fuel injection are stopped to prevent the watercraft from
accelerating suddenly.
Control is not activated over 1,000 r/min.
Quick acceleration mode
If engine speed is less than 4,400 r/min and the throttle is opened suddenly, ignition timing is
advanced by quick acceleration advanced correction.
Fuel injection occurs four times at acceleration as non-synchronous injection.
Cylinder #1
Cylinder #2
Cylinder #3
Cylinder #4
Throttle opening angle changes
Injector #1
Injector #2
Injector #3
Injector #4
Compression Combustion
Intake
Exhaust Intake Compression
Compression Combustion Exhaust
Combustion Exhaust
Intake
Injection
Stopped
Normal injection
Injection
Stopped
Injection
Stopped
Injection
Stopped
Exhaust
Intake
Combustion Exhaust
Compression
Intake
Compression Combustion
Acceleration determination
Next non-synchronous injection for intake stroke cylinder
When acceleration non-synchronous injection occurs 4 times
Current non-synchronous injection
for intake stroke cylinder
Fig. 23
21
Compression Combustion Exhaust
Intake Compression Combustion
Combustion Exhaust
Exhaust Compression
Intake
Intake