Fuel Injection Control - Yamaha WaveRunner FX140 Service Manual

FUEL INJECTION CONTROL

Basic fuel injection volume uses two control systems: The speed density system (D-Jetronic) 3D
map, which is calculated from the intake air pressure and engine speed, and the speed throttle
speed system (Alpha-N) 3D map, which is calculated from the throttle opening and engine speed.
The D-Jetronic and Alpha-N 3D map activity ratio changes according to the throttle opening angle.
If the throttle opening angle is less than 12°, D-Jetronic is used.
If the throttle opening angle is more than 12°, the activity ratio of D-Jetronic is gradually reduced and
the activity ratio of Alpha-N is increased.
If the throttle opening angle is more than 14°, only Alpha-N is used.
After the basic fuel injection volume is determined, each correction value is added to determine the
actual fuel injection volume.
(%)
100
D-Jetronic
Alpha-N
0
Close
Open
12 14 (deg)
13
Throttle opening angle
Fig. 25
23