1990 Johnson Evinrude "ES" 60 thru 70 Service Manual, P/N 507873, Page 222Get this manual
141 Starter System Voltage Drop TestAll Models
By making systematic check from the positive battery terminalthrough the starting circuit and back to the negative battery terminal, any component or electrical connection having excessive resistance can be located below
To prevent accidental starting of engine while servicing, twist and remove all spark plug leads
Clean and retighten, or replace, any connectioncable, or component having greater than specified voltage drop 1Connect voltmeter positive lead to battery positive post Connect voltmeter negative lead to starter solenoid positive terminalTurn key switch to "Start" to crank engine Voltage reading should not exceed .3 volt]