Fi System - Yamaha 2012 TMAX XP500A 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 a certain level. 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 pas-
sage 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 (engine control unit). Sig-
nals that are input from the throttle position sensor, crankshaft position sensor, intake air pressure
sensor, intake air temperature sensor, coolant temperature sensor, and O
(engine 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
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
sensor enable the ECU
2