Yamaha YFM700RV Service Manual

Also see for YFM700RV: Owner's manual Owner's manual Assembly manual

Contents

Yamaha YFM700RV Service Manual Manual pdf 18 page image

1 - 2GENINFOFEATURESEAS20170FEATURESOUTLINE 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 with 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.1 Engine trouble warning light2 Ignition coil3 Fuel tank4 Fuel hose5 Fuel pump6 Intake air pressure sensor7 Lean angle sensor8 Battery9 Intake air temperature sensor0 ECU (electronic control unit)A Air filter caseB Relay unit (fuel pump relay)C Speed sensorD Throttle position sensorE Crankshaft position sensorF Fuel injectorG Coolant temperature sensorH Spark plug1 2 3 4 5 6 7 8 9 0 A BCDEFGH1