ryobi starts, then dies...

My Ryobi 31cc starts right up after i prime it, but then dies 5 seconds later, waiting for me to prime it again. I have tried every possible hi/lo speed needle setting, but the same thing happens. There is no obstruction in the fuel line. It just seems as though the carb is not drawing in the fuel...? What should I do?

Thanks.

One thing is make sure your gasket is not blocking the pulse hole on the carb, and make sure your diaprahm isn't dry rotted... Hope this helps.