How to prime your carburator - Generac Power Systems Generac 0057890 3250 Watt Gasoline Generator

Check out the tubing to the carb. If it is good then the top part of the carb with the check valves is defective. If so, you need a new carb since those suckers cannot be fixed.

replace the primer
check for broken hose to fuel tank

See if it has a priming bulb by the carburator, maybe it's dried out and cracked and not able to build pressure

Your question doesn't make sense,If primer bulb is going flat you have a blockage between primer and tank.also check fuel vent on tank is open

If the primer buld is hard to push or wont return to shape like its supposed to then there is an obstruction in the carb. If it just wont move fuel then there is a hole in the fuel line or the fuel line is rotted off in the tank.
If the primer bulb itself is discolored ( should be clear not brown) it should also be replaced.

sounds like the carb needs a good cleaning and the primer bulb replaced

Check to be sure there isn't a small hole or crack in the priming bulb. If there is it allows air to enter fuel line, loosing the prime. Most have a collar that unscrews to remove it.

the fuel thank have 2 lines the one is close to you facing out is the pick up line this line has a fuel filter inside the tank, thats mean go thru the carburator or adapter coupling thru the carburator in the bottom. The second line is the return line this line go thru the prime valve on the bottom and the top line go thru the top line tube in the carburator.

If it's coming from the primer bulb, replace the bulb. If it's running out the carburator, take iff the air filter and check for obstructions. 2 - 3 pumps is all it should need.

Are you sure that that the replacement is the correct one. Also, why did you have to replace the carburetor . Did you verify that the carburetor was the problem? Did the weedeater run by priming? Did you check the pump and lines? If these methods were tried and did not reveal the problem, then I suggest that you get professional help.