Have you done a simple fuel flow test? Open the float bowl drains to see if fuel flows freely. Open them both up for a minutes with hoses attached and drain into a glass. If they don't flow, disconnect the hose from the carbs and drain again. Keep doing it till you find the blockage. I agree about the inline filter acting up.
I'm assuming it is a blockage since your bike ran good until you played with the fuel tank. Have you removed the petcock from the tank and checked the screen?
