Fi System - Yamaha YFM7FGPW Service Manual

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 kg/cm
ingly, 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. 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 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, 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 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.
Illustration is for reference only.
C
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
0 Throttle body
1
2
È
A
É
B
0
9
1 - 3
FEATURES
5
Ê
4
6
7
3
8
A Throttle position sensor
B Intake air temperature sensor
C Air filter case
È Fuel system
É Air system
Ê Control system
GEN
INFO
2
, 46.1 psi). Accord-