I did a little checking on the fuel system today.
First I pulled the gas line at the carb, put the end in a tin can, and cranked for about five seconds. No gas.
Next I unscrewed the filter can. There was a very little dirty gas in the bottom, but the filter didn't look dirty, so I put it back in for now.
Then I pulled off the line coming from the tank at the carb. Gas ran out like it should.
I went back to the carb line and put it in the can again. When I cranked this time, It started filling the can.
I put the line back on, and on the third try (pouring a little gas in the carb each time) it stayed running on its own.
I haven't driven it on the road yet, but it acts like nothing is wrong.
Vapor lock? Dirt in the line that got knocked loose?