My son has a 94 Mustang, LX 6 cyl. Gets 10 mpg, maybe 12 mpg hwy. When running, get gasoline smell. Had major tuneup done along with replacing gas tank and filler tube (repair shop said was leaking). No leaks apparent afterwards. Could it be oxygen sensors bad? Son also installed aftermarket air intake, though we had same problem before installation. Looking for any advice.
Thank you,

Chris

Hard to say but I would think a leak as well. It could be a small leak, that only happens while driving and the system is in use. Especially with the smell of gas. rememeber gas can evaporate, so if there is a small enough leak, you may not see it.

Take it back to where you had the tank replaced make them fix it, or was it getting that mpg before the tune up?

Mileage was poor before gas tank and filler tube replacement. We took it in to check for gas leaks as the smell was very noticable prior to tank replacement. Can't find any fuel leaks and for a 6 cyl engine, mileage should be better than 10 mpg. Any other thoughts?

It may sound like alot of work but with the price of gas, I think it will be worth the time investment. I'd follow the fuel lines from the tank to the motor, looking for any dry or cracking fuel line. Gas is a very volatile compound, meaning that it vaporizes relatively easily. So you might not see the leak, but if you can smell raw gas you're either leaking gas or burning it inefficently. The tune up rules out the later of the two possibilities. Good luck.