Fi System - Yamaha 2009 Diversion XJ6S Service Manual

EAS4B51039

FI SYSTEM

The fuel pump delivers fuel to the fuel injector via the fuel filter. The pressure regulator (in the fuel
pump) maintains the fuel pressure that is applied to the fuel injector at 245–255 kPa (2.45–2.55 kgf/
2
cm , 35.5–37.0 psi) higher than the intake manifold pressure. Accordingly, when the energizing signal
from the ECU (engine control unit) 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. Therefore, the
longer the length of time the fuel injector is energized (injection duration), the greater the volume of fuel
that is supplied. Conversely, the shorter the length of time the fuel injector is energized (injection dura-
tion), the lesser the volume of fuel that is supplied.
The injection duration and the injection timing are controlled by the ECU (engine control unit). Signals
that are input from the throttle position sensor, crankshaft position sensor, intake air pressure sensor,
intake air temperature sensor, coolant temperature sensor, and O
control unit) to determine the injection duration. The injection timing is determined through the signals
from the crankshaft position 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.
1. Fuel pump
2. Fuel injector
3. Ignition coil
4. ECU (engine control unit)
5. Catalyst
6. O sensor
2
7. Coolant temperature sensor
8. Crankshaft position sensor
9. Intake air pressure sensor
sensor enable the ECU (engine
2
10. Throttle body
11. Intake air temperature sensor
12. Air filter case
13. Throttle position sensor
A. Fuel system
B. Air system
C. Control system
1-3
FEATURES