50 hp 2-stroke stalls shortly after startup

I have a new 50 hp 2 stroke on my pontoon boat. After I start it up and wait for the trailer to be parked the motor dies after approx. 2-3 minutes while idling and warming up. The only way I can restart is to pop the cowling and move the red emergency lever to the down position. On a windy day this is dangerous. The motor is three months old and this happens more times than not. Took to dealer and it worked fine. Next time out to lake it died. Could the check valve in the tank line to the motor be bad or is this a more serious mystery? Hans

After I get it started it works fine for the rest of the day.

[boats.net]

When it shuts off reprime fuel primer bulb to see if it's running out of gas.

Last time out it stalled after launching as before. This time I re-primed the bulb as you suggested. Before trying to restart I primed and primed and primed.(more than necessary you would think) I was able to get it started and after a rough idle I got it running as it should. This causes me to think it is getting an air-lock between the tank and engine. Anymore suggestions?

[boats.net]

You might try a new fuel hose, check all connections.