Electronic Fuel Injection Control System - Yamaha F150B Service Manual

TECH
FEA

Electronic fuel injection control system

F150B uses electronic fuel injection control system to control the fuel injection timing and the
amount of injected fuel. The fuel injection amount (example: duration of fuel injector energization) is
controlled to assure the appropriate air/fuel ratio based on the intake air flow rate calculated from
intake pressure and engine speed, responding to every engine operating condition represented by
the signals from each sensor. High output power, improved fuel economy, and low exhaust emis-
sions are attained by this system. Two types of fuel injection are carried out. One is synchronous
injection in which the fuel injection always occurs at certain crankshaft angle, after the required com-
pensation is made in accordance with the signals from each sensor. The other is asynchronous
injection in which the fuel is injected regardless of crankshaft angle, once the demand for the fuel
injection is detected in the signals from each sensor.
Block diagram
Pulser coil
TPS
Neutral switch
Air pressure
sensor
Air temperature
sensor
Engine temperature
sensor
Main battery
Thermoswitch
Engine shut-off switch
2-5
Technical features and description
Crankshaft angle,
Engine speed
Throttle valve opening
Neutral position
Intake air pressure
Intake air temperature
Engine temperature
Battery voltage
ON/OFF
Emergency stop
Fuel injector drive
signal
Engine
ECM
High-pressure fuel
pump drive signal
Fuel injector #1–#4
Fuel supply
High-pressure
fuel pump