Fi System - Yamaha XP500 Service Manual

EAS00897

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 240 ~ 260 kPa (2.40 ~
2
2.60 kg/cm , 34.1 ~ 37.0 psi) higher than the intake manifold pressure. Accordingly, when the ener-
gizing signal from the ECU (engine) 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
volume of fuel that is supplied. Conversely, the shorter the length of time the fuel injector is ener-
gized (injection duration), the lesser the volume of fuel that is supplied.
The injection duration and the injection timing are controlled by the ECU (engine). 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
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 sup-
plied at all times in accordance with the driving conditions.
B
A
Illustration is for reference only.
1 Fuel pump
2 Fuel injector
3 Ignition coil
4 ECU (engine)
5 Catalyst
6 O
sensor
2
7 Coolant temperature sensor
8 Crankshaft position sensor
2
È
1
É
0
9
9 Intake air pressure sensor
0 Throttle body
A Intake air temperature sensor
B Air filter case
C Throttle position sensor
FEATURES
sensor enable the ECU (engine) to
2
Ê
4
3
7
8
1 - 3
GEN
INFO
C
5
6
È Fuel system
É Air system
Ê Control system