[JohnB]

95% of the time, it's the primer bulb, I always carry a spare, and I have had new ones that were bad. If it isn't that, then try it with a 6 gal pony tank. Hook the pony tank behind the filter so you can rule that out. If it works fine with the pony behind the filter, your looking at stuck anti siphon valve in the gas tank.

I had a 140 johnson do that in Sebastian Inlet headed out one day, it was the anti siphon. This alcohol gas is "cleaning" everyones fuel system, and you probably have junk in the anti siphon valve. The suction lifts the stuff up into the inlet tube, but not all the way, so the stuff drops down, but not past the check ball, and you get restriction over time. I have seen 5 boats since we went on to alcohol do this.