I have a 1990 Waverunner 650. It started and ran good up until this afternoon. In fact it idled back to the trailer but would not start when I got home. I did run it out of gas and had to go to reserve while on the last ride. When I got it home it would not start. I filled it up with gas and switched it back to the main fuel setting. It still would not start. I have checked spark by inserting a screwdriver into the plug wire and cranking the engine while holding it close to the block and I have spark. Is there some sort of prime that I need to do? There does not seem to be any fuel coming out of the fuel filter. Does the fuel draw to the carb or does it work on gravity feed. Help!!!