1996 scarab mercuiser 502 motor was running fine just shut off went home turned key on coil started smoking replaced coil new one did same thing changed ingition modual still smoked coil what to do

inline resister went bad? does it smoke when only running? if so check you alternator output voltage,should be 13,8-14.2...if its reading higher then your alternator is over charging and sometimes the alternator will throw a/c voltage into the system and kill every electrical component in the boat..

found the grey wire that goes to the tach and splits to a wire that is not connected to anything has bullet style connector.
The wire with the bullet connector was short to ground on the block. fix the short engine started and coil overheat fixed . does anyone know what that wire do.

What color was the extra wire you found ?

the wire was grey in color but was connecter to nothing

Nothing in the merc wiring diagram shows that extra wire. Someone may have added it for who knows what...lol. Obviously you didnt need it before. Just tape it up good, and forget about it sir.

thanks took boat out ran fine except oil pressure drops over 3500 rpm 40 at idle but happy went and came under own power