I own a 2010 VW Polo (not sold in USA). I'm having a very particular warm start problem. Whenever the car has a half full gas tank and I drive it for about 20-25 minutes in warm weather (around noon, around 87 °F), I park it and let it cool for about half hour, the car won't start. The symptoms are normally cranking without firing or just not starting.
The car will start with difficulty at the third or fourth attempt.
For the rest of the day the car usually starts fine. What do you think could it be?
Thanks for your help!