1996 Johnson/Evinrude Outboards 25, 35 3-Cylinder Service Manual, Page 115Get this manual
Output Tests
All cranking output tests must be performed with spark plugs installed and torqued in the cylinder headIf necessary to remove the spark plugs, be sure to keep the spark tester away from open spark plug holes
STEPTOTAL OUTPUT TEST
To avoid electrical shock, do not handle ignition coil or spark tester during cranking tests1Twist and remove all spark plug leads