Small Engines (Lawn Mowers, etc.): Ryobi 770r trimmer carburetor wont prime, gas trimmer, ryobi

Question
I've replaced the fuel lines, filter and primer bulb on my Ryobi 770r gas trimmer.  For some reason, when I try to prime the carb the gas dosen't fill the bulb and enter the cabruretor.  I've checked the lines and there are no leaks.  I seem to hear a slight squeak coming from the carburetor with each pump on the bulb.  Could the carb be bad?

Answer
Dave
Sounds like a venting problem. The way the primer works is it draws fuel from the tank to the bulb,then the next prime sends fuel to the carburetor and draws more fuel. There has to be a venting to allow the prime cycle to work or else it will cause a vacuum not going anywhere.