Mercury Mariner V-250 V-275 Outboard Service Shop Manual 1990, Page 27Get this manual
PartIgnition System Description
T he V-6 outboard ig nition system is alternator-d riven with distri butor-less capacitor dischargeMajor components of the ignition system are he flywheel, stato assemblytrigger assembly, switch boxes, ign ition coil and spark plugsThe stator assembly is mounted stationary below he flywheel and has capacitor charging coi lsT he flywheel is fitted with permanent magnets insid the outer rim As th flywheel rotates the permanent magnets pass the capacitor charging coi lsThi causes the capaci tor charging coils to produce AC voltageThe AC voltage then is conducted to the switch boxes where it is rectified and stored in capacitorThe trigger assembly (also mounted under the fl wheel) has coi ls The fl ywheel likewise has second set of permanent magnets (located around the center hub) As the fl ywheel rotates the second set of magnets pass the trigger coilsTh is causes he trigger coil s, in turn, to produce an AC voltage that is conducted to an electronic switch (SCA) in the switchbox
The switch discharges the capacitor voltage into the ignition coil at the correct tim and in firing order sequenceCapacitor voltage is condu cted to the primary side of the ignition coilThe ignition coil multiplies th is voltage to va lu high enough to jump the gap at the spark plug Th preceding sequence occu rs oncepereng inerevolution for each cylinderSpark timing is cha nged (advanced retarded) by rotat ing the trigger assembly which changes eac trigger coil position in relation to the permanent magnets located around the flywheel center hub