Yamaha Marine Outboards Factory Service / Repair/ Workshop Manual 225G 250B L250B, Page 321Get this manual
FUEL CONTROL SYSTEM
Measuring steps
WARNING
To prevent an explosion when performing this procedure, keep all flammable products (e.g gasoline) away from the testing area and make sure there is proper ventilation(1) Remove the oxygen density sensorRefer to "OXYGEN DENSITY SENSOR" on page 5-26(2) Remove any oil from the oxygen density sensor with acetone or similar solvent and allow the sensor to thoroughly dry(3) Heat the front end of the oxygen density sensor with gas torch (in the center of its blue flame a) for 10 15 secondsThen, remove the oxygen density sensor from the flame and check the voltage change and time