Features; Outline Of Fi System - Yamaha FZ6-SS 2004 Service Manual

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 carburetor.
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 air temperature
3
sensor
Fuel delivery hose
4
Fuel tank
5
Fuel pump
6
Intake air pressure
7
sensor
Throttle position sen-
8
sor
Fuel injector
9
Catalytic converter
10
Crankshaft position
11
sensor
FEATURES
Coolant temperature
12
sensor
Spark plug
13
Pressure regulator
14
Battery
15
ECU
16
Fuel injection system
17
relay
1-2
GEN
INFO
Engine trouble warn-
18
ing light
Lean angle cut-off
19
switch