Modern Vespa

After cleaning the carb I replaced the fuel filter because I found I had one I never used lying around and now fuel is not flowing to the fuel filter. The fuel pump, filter and fuel line were replaced 3 years ago. I'm thinking maybe I created an air gap or something between pump and ?carb when the fuel bled out of the line during the filter change.
Any tips on how to get fuel flowing through the line and filter again?
Thanks.

Well if the filter's different that'd be suspect no. 1. I heard from a friend who is absolutely not me that it's easy to put a fuel filter in backwards they will sometimes do strange things.

The fuel pump and petcock would be my other suspects. I think both are vacuum driven so if you've got no vacuum you've got no gas coming or going. Make sure the vacuum hose is hooked up correctly to both of those.

Thanks. Do you mean the vacuum hoses connected to the intake manifold? (which I also replaced because it was cracked.) The replacement manifolds have one less connection because of the evap system. Maybe I connected the remaining hoses backwards?