My friend has a '81 DeVille and the other day it wouldn't start. I watched the injectors as he turned the car over and no gas was coming from the injectors. We took the fuel filter all the way out to see if it was restricted, but still no gas. I unplugged one of the injectors and there for a second it sounded like it was going to start. Could the injectors need new O rings, washers and filters? There is also a large amount of carbon buildup all over the throttle body and injectors, so I'm guessing carbon is blocking the filters and restricting gas at the injectors. Any thoughts on what the problem could be? Thanks.