Yamaha FZ8NA Service Manual

Also see for Fazer FZ8-SA: Owner's manual Owner's manual Owner's manual

FEATURES1-2EAS20170FEATURESEAS39P1101OUTLINE OF THE FI SYSTEMThe main function of a fuel supply system is to provide fuel to the combustion chamber at the opti-mum air-fuel ratio in accordance with the engine operating conditions and the atmospheric tempera-ture. In the conventional carburetor system, the air-fuel ratio of the mixture that is supplied to thecombustion chamber is created by the volume of the intake air and the fuel that is metered by the jetused in the respective carburetor.Despite the same volume of intake air, the fuel volume requirement varies by the engine operatingconditions, such as acceleration, deceleration, or operating under a heavy load. Carburetors thatmeter the fuel through the use of jets have been provided with various auxiliary devices, so that anoptimum air-fuel ratio can be achieved to accommodate the constant changes in the operating con-ditions of the engine.As the requirements for the engine to deliver more performance and cleaner exhaust gasesincrease, it becomes necessary to control the air-fuel ratio in a more precise and finely tuned man-ner. To accommodate 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 optimumair-fuel ratio required by the engine at all times by using a microprocessor that regulates the fuelinjection 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 engineresponse, better fuel economy, and reduced exhaust emissions.