FS 36 weedeater won't stay running

It will run, for a few seconds.







When you push the primer bulb, the fuel comes up to the carb...but it does not stay. It drains back into the tank.



What holds the vacuum in the carb to keep the fuel up?



I think if I can stop the fuel from draining out of the fuel line...problem solved.



But, I have been wrong before.



thanks, Shift