Mercury Mariner 30/40 4-Stroke Outboard Service Manual 1998, Page 67Get this manual
IGNITION
Ignition Description
The ignition system uses COl (Capacitor Discharge Ignition)This system provides quick voltage buildup and strong spark required for high power and high performance enginesThe COl ignition system does not incorporate mechanically operated points, therefor making this CO unit virtually maintenance freeAs the flywheel rotates, electrical power (alternating current) is produced by the capacitor charging coilThis power is rectified by diodes so that direct current voltage is utilized by the ignition systemWhen the ignition driver is off, the D.Cvoltage is stored by the capacitorOnce capacitor voltage is charged to its potential, gate signal is applied on the SCR and the residual current is dissipated through the capacitor charging coilsThe electronic control module (ECM) activates the ignition driver in the ECM which allows the capacitor to discharge, causing the spark to occurIgnition timing is regulated by the ECM which receives status input from variety of sensorsThese sensors include the crank position sensor, engine temperature and oil pressure senderThe voltage discharged to the primary winding of th ignition coil causes surge of high voltage to be induced in the secondary winding of the ignition coilThis induced voltage of sufficient amplitude causes th spark plugs to fire