Yamaha YZF-R6R Service Manual page 19

EAS00896
FEATURES
OUTLINE OF FI SYSTEM
The main function of a fuel supply system is to provide fuel to the combustion chamber at the optimum
air-fuel ratio in accordance with the engine operating conditions and the atmospheric temperature.
In the conventional carburetor system, the air-fuel ratio of the mixture that is supplied to the combustion
chamber is created by the volume of the intake air and the fuel that is metered by the jet used in the
respective chamber.
Despite the same volume of intake air, the fuel volume requirement varies by the engine operating
conditions, such as acceleration, deceleration, or operating under a heavy load. Carburetors that me-
ter the fuel through the use of jets have been provided with various auxiliary devices, so that an opti-
mum air-fuel ratio can be achieved to accommodate the constant changes in the operating conditions
of the engine.
As the requirements for the engine to deliver more performance and cleaner exhaust gases increase, it
becomes necessary to control the air-fuel ratio in a more precise and finely tuned manner. To accom-
modate this need, this model has adopted an electronically controlled fuel injection (FI) system, in
place of the conventional carburetor system. This system can achieve an optimum air-fuel ratio re-
quired by the engine at all times by using a microprocessor that regulates the fuel injection volume
according to the engine operating conditions detected by various sensors.
The adoption of the FI system has resulted in a highly precise fuel supply, improved engine response,
better fuel economy, and reduced exhaust emissions. Furthermore, the air induction system (AI sys-
tem) has been placed under computer control together with the FI system in order to realize cleaner
exhaust gases.
Ignition coil
1
Air filter case
2
Intake temperature
3
sensor
Fuel delivery hose
4
Fuel tank
5
Fuel pump
6
Fuel return hose
7
Intake air pressure
8
sensor
Throttle position sen-
9
sor
Fuel injector
10
Catalytic converter
11
Crankshaft position
12
sensor
Coolant temperature
13
sensor
1-2
FEATURES
Spark plug
14
Cylinder identification
15
sensor
Pressure regulator
16
Battery
17
ECU
18
Atmospheric pressure
19
sensor
Fuel injection system
20
relay
GEN
INFO
Engine trouble warn-
21
ing light
Lean angle cut-off
22
switch
Air cut-off valve
23