Yamaha F100B F100C Outboards Factory Service Manual, Page 308Get this manual
Electrical systems
Checking the CDI unit
1Measure the CDI unit output peak voltageIf below specification, measure the Rectifier Regulator output peak voltage and pulser coil output peak voltageReplace the CDI unit if the output peak voltage of the Rectifier Regulator and pulser coil is above specification
Checking the ignition coil
1Remove the high-tension cords from the ignition coil2Measure the ignition coil resistanceReplace if out of specificationBW