Backfire In Rough Water
 

Thanks for the replies!

Maybe you need new spark plug wires and spark plugs. Your boat is older, so it may be time to change them.

had same problem, found loose connection on lanyard safety switch

If everything else checks out, I'd replace the coil - I had one that check fine on the bench, but when hot it would cut out at odd times. Vibration could do the same - lots of windings and a few connections in that coil.

definitely a wiring issue of some kind....Check all plugs switches connections ect

ttt

Hmmmm I will check this guy too!

U check the float bowls?
Buddys boat did same thing, dumping fuel into carb, adjusted floats problem went away.

Yeah what he said.

Did you put a different carb on?

That is what we were thinking yes its a new Holley 850 Marine carb out of the box no adjustment yet. Thanks for all the replys OSO Rocks!!