I have a stock 1994 454 carb motor. it is almost impossible to start while on the water. once it is running, it runs good. if I shut it down it will start right up. if I let it sit for more than 15 minutes I have to hold the throttle wide open till it fires. it acts like its flooded. it's done this for as long as I can remember and I'm getting tired of the looks of Horror from people watching me try to start it again. any help would be great.