I have a 2002 GMC 3500, Duramax, with 89,000 miles . I am experiencing a raw fuel smell around the truck when it is running and a light colored smoke condition from the exhaust, (which also smells of raw fuel). This condition is especially noticable at idle. There are no obvious signs of a fuel leak. I believe my fuel mileage has also dropped considerably. It is almost like the truck is running to rich. Any suggestions or comments would be appreciated.