1998 Johnson Evinrude "EC" 9.9 thru 30 HP 2-Cylinder Outboards Service Manual, Page 288Get this manual
Starter System Voltage Drop Test
By making systematic check of the starter system, any component or electrical connection having excessive resistance can be located
accidental starting of engine while servicing; twist and remove all spark plug leadsClean 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 voltIn Step 2, connect the voltmeter leads only while the engine is cranking, or damage to the voltmeter can occur