Leaf Blowers

I have a Husqvarna 350bt backpack blower that I bought less than a year ago. It has been in my shed for 8 months. After many pulls it starts with the gas line closed. When I edge the lever up the slightest, it stalls. I let it run for 30 mins in the closed position, but if I pull the trigger or open the gas line, it immediately will die. I drained the gas and put in the Husqvarna already mixed gas/oil, but it still is happening.