I have a troy bilt weed eater that worked fine last year--it is two years old. I removed the gas mixture and put in new. It will not start. When primed it pushes gas to the carb but when I release the primer bulb it sucks the gas back out ot the carb. When I pull the starter rope it fires once or twice and stops. Is the primer bulb defective? Thank you

Hi.
The jet at the bottom of the flost bowl is clogged. Remove it and clean to be good to go.
Peace,
Clarke