So I took the cover off and eyeballed the leak(s). 3 out of the 4 carbs were leaking, but the worst leak was on the bottom left. They all seem to leak around the top of the bowl, so I guess the bowl gasket isn't sealing.
On one carb the screw plug for the high-speed jet was loose.
The carb that was leaking the worst was leaking fuel from the Idle Air Bleed Orifice.
I have to confess that I rebuilt these carbs about 10 years ago and only used the boat a few times after that and then it sat for 8 years.
I probably did not do things correctly which is probably why they are leaking.
I can rebuild them again, but how do I get the bowl gaskets to seal correctly? Also, on all of my carb rebuilds I have had problems with those carb body spaghetti seals, they always seem to stretch out and won't fit in the groove properly. Any tips or advice to avoid this problem?