Ive got a gen 5 carbed 454, 420HP that has a little issue... it will start up in the morning, i can run it to lunch (about an hr) turn off the motor and eat lunch (about 1.5hrs), go to the boat and it starts right up, but then i go and anchor out, let it sit about 4 hrs, and it wont start, the 4 hours it sits is the hottest and most humid part of the day, im thinking it could have soemthing to do with that,

i usually go back to the ramp on one motor, then the next day it will fire right up again in the AM.... any ideas??

Is the boat rocking a lot when anchored? could be a fuel float issue causing the motor to flood.

Could water be running of the hatch and getting the ignition wet (from swimmers)

You have to be more specific with your symtoms. Does it crank, clicking noise, or???

swap out the coil .....

Your not taking a long enough lunch !!

I've seen the fuel vapor lock when it's hot, just a suggestion.

that was my first thouht...

It sounds like vapor lock, usually a coil goes all at once, no hit or miss, it could also be the slave solinoid, does it click once when the key is turned but not engage the starter? It sounds like a vapor lock the more I think of it but after 4 hours that should clear. If the engine is hot the fuel will boil and vaporize and leave a pocket of air that locks the fuel system. On the slave, you can turn it and hear a click, keep doing it and it may fire but most of the time they have moisture in them. It is very common after storage to have this go out. This is a fun one to find, you can swap out the entire electrical system and find it is fuel or the other way around. I would say fuel though, maybe lift the hatch while sitting, run the blower to pull the hot air out. Still 4 hours is enough time to let this rest.

I'm not a mecanic to that point, but I would think float problem... I'd switch the carb first. Does not take too long to do it!

coil swap is easier and faster than swapping carbs.....