Boat won't shut off

[Mbalafas]

Ok so here goes. Few weeks ago I was working on the boat and had to fix a wire connection out of the alternator. The wire in question had a rubber block on it. Well llong story short the rubber block is gone. Up until the other day boat would shut off fine, however now all of a sudden it only shutd off when I oull the top wire out of the distributor. I've been looking and most sources point to a diode. Anyone know whats going on?
the engine is the aq125a

 

[Bt Doctur]

blown diode or bad alternator backfeeding the ign system

 

[alldodge]

Agree has to be back feeding, but I'm not seeing a diode in the schematic

 

[Mbalafas]

So new alternator?

 

[alldodge]

So new alternator?

Don't know, have not done enough testing but don't think so. The coil only has one wire coming from the key to the + side of the coil. The + side of the coil should only have one wire on it, is this true?

If there is only one wire then need to check the wiring on the key switch