BMW Repair: 95 BMW 318ti Fuel Smell, bmw 318ti, hot weather

Question
Last year this car developed a fuel smell that went away during the winter. Now that it's warm again, the intermittent fuel smell is back. It seems to be strongest when the car has been driven for awhile and is subsquently parked. Although it sometimes smells while I'm driving. I cannot see any leaks. What do you think is the cause?
Thanks

Answer
sounds like a problem with the evaprative emissions system.  During the hot weather, the fuel in the tank especially when driven for a long time or parked in the sun will evaporate and cause more pressure in the tank that needs to be turned back to a liquid.  check the charcol canister and all the fuel related lines.  If you smell fuel you should be able to see where it's coming out.
-cheers