1991 Yamaha Outboard Factory Service Manual 9.9 and 15 HP, Page 103Get this manual
ELECTRICAL OEseR IPTION
WARIlING:
This model employs the capacitor discharge ignition (COl) system in which single ignition coil is used to produce sparks simultaneously in both the upper and lower cylindersHowever, ignition only takes place in the cylinder which is on the compression strokeThe lighting coil delivers an 80 using 4-pole magnetooutput of
Before starting the disassembly, assembly, or checking of electrical parts, be sure to remove the battery wires and the spark plug cap