1985 Cadillac El Dorado Car Simply Stopped Would Start Again Spark Plugs

The car simply stopped and would not start again. The spark plugs are sparking, and the starter is cranking. The engine simply will not fire. I changed the fuel filter. It seemed to be the original, and it was a bit clogged, but the new filter did not solve the problem. How do I determine if it is a) indeed a fuel problem b) if the fuel pump is operating properly or c) what else could it be? Thank you