Fi System - Yamaha Grizzly550 User Manual

EAS28P1032

FI SYSTEM

The fuel pump delivers fuel to the fuel injector via the fuel filter. The pressure regulator maintains the
fuel pressure that is applied to the fuel injector at only 324 kPa (3.24 kgf/cm², 46.1 psi). Accordingly,
when the energizing signal from the ECU energizes the fuel injector, the fuel passage opens, causing
the fuel to be injected into the intake manifold only during the time the passage remains open. There-
fore, the longer the length of time the fuel injector is energized (injection duration), the greater the vol-
ume of fuel that is supplied. Conversely, the shorter the length of time the fuel injector is energized
(injection duration), the lesser the volume of fuel that is supplied.
The injection duration and the injection timing are controlled by the ECU. Signals that are input from the
throttle position sensor, crankshaft position sensor, intake air pressure sensor, intake air temperature
sensor, coolant temperature sensor, lean angle sensor and speed sensor enable the ECU to determine
the injection duration. The injection timing is determined through the signals from the crankshaft posi-
tion sensor. As a result, the volume of fuel that is required by the engine can be supplied at all times in
accordance with the driving conditions.
Illustration is for reference only.
14
1. Fuel pump
2. Fuel injector
3. Ignition coil
4. ECU (engine control unit)
5. Speed sensor
6. Lean angle sensor
7. Coolant temperature sensor
8. Crankshaft position sensor
9. Intake air pressure sensor
10. Throttle body
11. ISC (idle speed control) unit
12. Throttle position sensor
1
2
A
12
B
13
11
10
9
1-3
5
C
4
6
7
3
8
13. Intake air temperature sensor
14. Air filter case
A. Fuel system
B. Air system
C. Control system
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