2003 ST 4 Stroke 9.9/15HP Johnson outboards Service Manual, Page 57Get this manual
IGNITION AND ELECTRICAL IGNITION SYSTEM
IGNITION SYSTEM
Principles of Operation
The ignition system is condenser discharge typeThe condenser built in the COl unit stores the electrical energy generated by the condenser charge coilThe electrical energy stored in the condenser is released to the ignition coil primary windings by the signal from the pulser coilThe ignition timing varies based upon engine speed The timing remains at degrees BTDC until engine speed reaches 1300 rpm and advances up to 30 degrees BTDC until engine speed reaches 3500 rpm The timing will not advance after engine speed reaches 3500 rpm
Caution System