My car is a 94 Nissan Altima (2.4 litre). What might cause it to consume huge amounts of fuel? (it uses up 3/4 of a tank on a 20 mile round trip across town - no traffic - no idling etc.). Other symptoms - runs very rough with diminished power - produces huge dense clouds of smoke that smell a bit like gas. This is a somewhat intermittent behaviour. There is a tiny exhaust leak either at the head/manifold or manifold/exhaust pipe connection. (the sound is similar to a bad muffler, but originates under the hood near the motor)
I have some suspicions - flakey electrical component (fuel controller?) or flakey injector.
My troubleshooting resources are extremely limited and some feed back to get me on the right track is greatly appreciated.
Thanks
NK