2001 Ford Taurus

Whenever I drive my car in hot weather and turn the car off, it does not restart. The car sounds like it has no gas, but the tank is full. I was told by a mechanic to bleed the line in front of the engine a little, and it usually starts up with no problems afterwards. It was fine during the winter and as soon as the weather began getting hot, this started. A friend of mine hooked up his computer and found no codes, he said it could be the fuel filter regulator. We had the fuel filter replaced not too long ago at Ford. What could be causing this?