Scooter won’t start

[Witelic]

Hi,
New poster here. I just acquired a 50cc gy6 scooter. It ran ok, I shut it off and it sat for a few weeks in the garage. When I went to start it, starter spins engine over just fine but it won’t fire. I did replace the spark plug, as it seemed spark was weak, I even put in a new CDI box. Today I tested gas flow, none flows from gas line at the carb when I crank the starter. I pulled off the vacuum line from the intake manifold, which goes to the vacuum petcock. When I suck on this line, gas flows from the fuel line going to the carb. So, it seems the vacuum petcock has failed. Does this seem right?
Anyone ever have a similar problem? How did you fix it? Put in a manual petcock with a remote shutoff valve in the fuel line? Any suggestions?