1999 EE Johnson Outboards 25, 35 3-Cylinder Service Manual, Page 110Get 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
2Adjust the gap on the spark tester to 38 in(9 mmlConnect tester leads to the spark plug leadsSecure tester clip to clean engine groundTo prevent high voltage arc, route tester leads at least in (51 mml from any metal surface