Mercury Mariner 4 and 5HP 4-Stroke Outboards Service Shop Manual 1999, Page 61Get this manual
IGNITION SYSTEM
Ignition Coil
REMOVAL
1Disconnect BLACKIYELLOW CDI unit lead (a) from coil (b)
2Disconnect high tension plug lead from spark plug3Remove bolts (c)and washers (d) and remove coil while disconnecting BLACK ground wires (e)