1988 Johnson/Evinrude "CC" 40 thru 55 Models Service Manual, Page 261Get 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
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 volt