2006 Johnson SD 3.5 HP 2 Stroke Outboard Service Manual, PN 5006562, Page 61Get this manual
IGNITION SPARK PLUGS Surface Leakage Test The ignition coil and spark plug lead should be tested for leakage or insulation failures using the ignition analyzerLeakage is caused by moisture, cracks, or holes in the coil housing or spark plug leadsWith the analyzer's black and red leads still connected from the Power Test, remove the analyzer's high tension lead from the coilTurn on the analyzer and probe the entire surfaces of the coil, spark plug lead, and spark plug cover
SPARK PLUGS
Remove and inspect the spark plugs for the following conditions: Worn electrodes Cracked insulator Dirty spark plugs Replace all defective spark plugsBefore installing the spark plug lead cover on the spark plug, apply light coating of Electrical Grease to the ribbed portion of the spark plug ceramic and to the opening of the spark plug coverSee table below for recommended spark plug data and gap setting