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Electrically issue

Darren M

New member
Need some help with an electrical issue. 1990 mercruiser 3.0. When the key is on, the wire that comes out of the ignition coil (grey/green) runs to solenoid, wire gets red hot and runs really rough. When the wire isn’t hot it runs nice. Don’t I know if it’s coil, solenoid or maybe key switch. Any help is appreciated. Thx
 
Grey green sounds like a tach signal wire? Are you running points? Disconnect and isolate that wire and see if it starts up? Then run it and see if the coil gets hot? Hopefully that wire did not light up the harness. You definately need a good wiring diagram and check for internal shorts in the loop from the helm to the engine. Wire fires can be fatal out on the water be thorough.
 
It has points.2 wires go to power side of coil one purple and then one looks green but it’s burnt. When I disconnect the hot one engine will crank but not start. The coil doesn’t get hot though only that one wire when the key is on or running.
 
The nearly 30 year old wiring is questionable. If the boat saw any salty water, the chances are that the wire inside the insulation has corroded and it is getting hot because it is not able to carry the current any more. Please don't use the boat with glowing hot wires! You may find yourself floating several feet above your body wondering why you feel so light and what that big bright light is coming from above.
 
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