Fuel Injection problems of the 2000 Cadillac Deville

Gas-like fumes are coming through the air vents and air-conditioning in the car while driving in the city and on the highway. I have reported this to customer service for Cadillac. This is the third time I have taken my car in for the gas -like fumes. Two times the engine/motor was cleaned because there was a very bad carbon build-up. On April 9, 2002 I took my car back ( 3rd time). I was told the fuel injection system needs to be replaced. So far, I have not heard from the service dept. At Cadillac of memphis. This part was supposed to be ordered the very same day. There have been several complaints in this area from consumers about the gas-like smells in their cars. I need to know if this will cause a health risk because I don't know how much carbon I have been inhaling. No one is telling consumers why this problem is occuring. Every time I have to take my car in I have to miss one day of work of which I am not paid. Maybe we will get some answers with your help. Thank you!.