Fi System - Yamaha XT660R Service Manual

EAS00897

FI SYSTEM

The fuel pump delivers fuel to the injector via the fuel filter. The pressure regulator maintains the
fuel pressure that is applied to the injector at 324 kPa (3.24 kg/cm
manifold pressure. Accordingly, when the energizing signal from the ECU energizes the 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 injector is energized (injection
duration), the greater the volume of fuel that is supplied. Conversely, the shorter the length of time
the 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 tem-
perature sensor, and coolant temperature sensor enable the ECU to determine the injection dura-
tion. The injection timing is determined through the signal 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 Pressure regulator
3 Fuel injector
4 Throttle body
È
#1
3
6
9
5 Intake air temperature
sensor
6 Throttle position sen-
sor
7 Intake air pressure
sensor
FEATURES
2
, 46.1 psi) higher than the intake
É
5
4 7
Ê
8
0
8 ECU
9 Coolant temperature
sensor
0 Crankshaft position
sensor
1 - 3
GEN
INFO
2
1
È Fuel system
É Air system
Ê Control system