Last year this engine ran great. This year I take the boat out and the engine will crank over and start fine, many times. At other times I turn the key and nothing happens - it is like the battery is completely dead (It is not), not even a click from the starter. I ran the boat across the lake and turned the engine off as I waited in line to load my boat, when I went to start the engine absolutely nothing! When I got the boat home, no problems, any clue as to what might be occurring?