I have an Oldsmobile that will not start. When I turn the key the engine attempts to turn over. The battery is working fine. It seems as though the car does start VERY briefly and then stalls out. When I do this lots of smoke comes out of the exhaust. The car was sitting for a while before I noticed this problem....I checked and there wasn't a pool of gas under the car, in case the fuel line was ruptured or something. I also checked the gas gauge which reads half a tank. What is wrong with my car? and is there anything I can do to fix it...other than taking it to a garage? Can I do an easy diagnostic myself or does this sound like a complicated problem?