Like Porschephd said, vapor lock. If you don't maintain fuel pressure it bleeds off and the remaining fuel in the line vaporizes when the engine is hot. When that happens your car is trying to start on fumes. After the engine cools the fuel condenses back to a liquid, albeit a low pressure liquid. Once you start the car, the pumps bring the pressure back up and will maintain liquid seal in the fuel lines until to shut it down and vapor lock occurs again. I'm betting it cranks over a few times before starting when cold, not a lot, but more than it should. Mine did as pressure built, after replacing the accumulator it fires almost immediately. Check your pressures, it's the most basic thing you NEED to do to insure a proper running car.
Mark 1979 930 Euro ***GONE AND DON'T MISS IT AT ALL***
"Worrying about depreciation on your car and keeping mileage down is like not ****ing your girlfriend so her next boyfriend finds her more appealing"