1990 Johnson Evinrude 120 thru 140, 185 thru 225, 300 HP, P/N 507875, Page 320Get this manual
Starter System Voltage Drop Test By making systematic check from the positive battery terminal, through the starting circuit and back to the negative battery terminal, any component or electrical connection having excessive resistance can be located below
'" To avoid accidental starting of engine while servicing, twist and remove all spark plug leads
Clean and retighten, or replace, any connection, cable, or component having greater than specified voltage drop
r:J 1Connect voltmeter positive lead to battery positive postConnect voltmeter negative lead to starter solenoid positive terminalTurn key switch to "Start" to crank engineVoltage reading should not exceed 0.3 voltINotelln step 2, connect the voltmeter leads only while the engine is cranking, otherwise damage to the voltmeter may occurf4l 2Connect voltmeter negative lead to the starter side of the starter solenoid terminal onlyWhile cranking engine, connect voltmeter positive lead to starter solenoid opposite terminalVoltage reading should not exceed 0.2 voltRemove voltmeter positive lead from starter solenoid and stop cranking engine'sl 3Connect voltmeter positive lead to starter solenoid, starter lead terminalConnect voltmeter negative lead to starter motor terminalTurn key switch to start engineVoltage reading should not exceed 0.2 volt1sl 4Connect voltmeter positive lead to battery negative lead common powerhead ground screwConnect voltmeter negative lead to battery negative postTurn key switch to start engineVoltage reading should not exceed 0.3 volt