So my buddy has a Donzi 28 ZX, twin 350 mags, with Bravos.

the tach has a little moisture in it, and after the winter, he takes it to the water for a test drive/ day out. after idling through the harbor, he notices smoke coming from the Port tach, and that motor shuts down..

so after some research its the tach it self, but it takes some time before a problem but it will not start back up with that tach... he can swap tachs (left to right) and the Starboard motor wont start, but the port will. SO the problem is all in the tach.

By why in the world would a bad tach shut the motor down?

probably grounding out the ign lead in the tach

Yep

Short to ground.

Thanks guys, I was told this about 20 min after i posted this ha. and everyone says the same thing.

Do a search and you'll see how common this is - minus the smoking part.

Better to be a tach smoker than a pole smoker.

Unhook it and go.