Primer Bulb?

i have a ght22 hedgetrimmer the primer bulb gets stuck in when i press it it stays in i just change the fuel lines also i took the vent line and the fuel line off to check and it and it stays in if i loosen the 4 little screws that hold it in and release vacuum it pops back out i guess my problem is it wont prime if i put fuelin thecarb it fires up then quits i need help please