What does the line from the fuel filter connect to? A pressure operated fuel pump perhaps. Or does it go directly to the carburetor? You may have a bad fuel pump.
Gravity fed. Piddled some more, noticed some fuel in the filter but not high enough to reach the outlet. Put more fuel in, weight didn't help. I then 'palm pumped' the tank fill hole and apparently was able to put enough pressure into the tank to push the fuel over the edge. It then began flowing out of the filter....hooked up the line and started it, and ran it about 5 minutes.
So I guess when it's sets for a while with the fuel tank shut off, I'll have to plan on manually 'priming' the filter to get it to flow through the filter.