I have a 1992 Johnson 70hp on a pontoon boat, and just had a tune-up. I took it out this past weekend for the first time, and it ran great and started great for a couple of hours. But after our last stop, which was for about 30 minutes, it wouldn't start. I finally got it started after about 20 minutes. Any ideas of what might have happened ?

I can kick the tires and look, but without testing, there is only guesses, are you getting spark ? Proper amp? Any loose wires ? Is it getting fuel, is there any air leak in line, is the fuel filter getting clogged, how is the fuel pump ? Issues with carb ?