Suzuki outboard motors 1988 2003 repair manual., Page 31Get this manual
MAINTENANCE 3-15 Fig38 normally worn spark plug should have light tan or gray deposits on the firing tip (electrode)
Fig39 carbon-fouled plug, identified by soft, sooty black deposits, may indicate an improperly tuned vehicleCheck the air cleaner, ignition components and the engine control systemFig40 physically damaged spark plug may be evidence of severe detonation in that cylinderWatch that cylinder carefully between services, as continued detonation will not only damage the plug, but could also damage the engine
Fig41 An oil-fouled spark plug indicates an engine with worn piston rings andor bad valve seals allowing excessive oil to enter the combustion chamber
Fig42 This spark plug has been left in the engine too long, as evidenced by the extreme gap-Plugs with such an extreme gap can cause misfiring and stumbling accompanied by noticeable lack of power