Scooter starts with starter fluid, then dies

[Whack51]

I have a JCL 150cc GY6 scooter. I didn't ride it much during the winter, but I did take it around the block at least every couple weeks. Now that the weather has been nice, I wanted to take it out. It started a little rough, as expected, but then sputtered and died after several seconds. Since then, I have not been able to keep it running. The engine cranks just fine and will fire and start up if I spray starter fluid or gas into the intake, but once that burns out it dies.
So far, I have replaced the vacuum lines and drained the old gas and put fresh gas in. I have also disassembled the carburetor and clean the whole thing. Every part of the carb, including the jets are spotless. It is getting gas through the line and into the carb bowl, but for some reason it is not getting into the intake.
Any thoughts on what the problem could be?