cranks but no start

The car dose poor on gas and smells of fuel when it runs.  The check engine light has been on ever since I've had it.  I replaced the spark plugs a few months back, and the check engine light went off for a week or so.  It had more pep at first then began to run poor again over a week of lite driving.  What caught my attention was I had recently used some belt condintioner to stop the squeaking noise,  I soaked it good.  I took the air box off from the intake and started it, gave it alittle gas and heard a back fire then shut the engine off.  Put it back together to test drive, it was idleing ruff and when you would put it in gear it would miss under the load.  Now it cranks but no start.  Doesnt even sound like its getting a "tah", ta", tah" tah" sound. Just all starter on the flywheel.  I'm still thinking that the belt condintioner may have shorted the crank sensor, down around the belt.  But I havent located the sensor yet, I thought it was on the transmission side of the engine.  Not the pulley side, its been too cold at the moment to try to tough it out now.  Any suggestions would be much appreciated.  Thank You and God Bless.