vapor lock or fuel backflow?

For years I have had to crank the engine for 15-20 sec before it will fire after it has been parked for a day. I had a friend crank it and I watched the empty clear glass fuel filter (in line about 8 inches before the carb) finally fill with gas just before it fires up. Is the gas boiled off when I park the car with a hot engine or is the fuel flowing back down the fuel line? The pump is about two years old and does not have many miles on it. The car runs perfectly once started.
 
  • Sponsors (?)