1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 171Get this manual
Ignition system Tests Using An Ohmmeter100 Models
Ohmmeter tests are necessary to determine if the sensor coil or charge coil have failed in manner which could cause ignition failureResistance readings should be checked when the motor has completely cooled to ambient air temperatureThe higher temperature, caused by running the motor, will increase the resistance reading and may result in unnecessary parts replacement
Rough Running Engine100 Models rough running engine may be due to interaction of the power packs because of faulty isolation diode in power packsThe diode may be checked by using an ohmmeter set to high ohms scale Check each power pack as follows1
Disconnect the four-wire connector to timer base