Fuel pump failure can cause the engine to crank but fail to start. Diagnosis will show insufficient, or no fuel pressure, and fuel pump in the fuel tank will need to be replaced.Google+
Car Problem Reports
Mercury Topaz Engine Cranks, but will Not Start - No Fuel Pressure
Mercury Topaz Problem
Engines Affected: 2.3L 4 Cylinder, 3.0L V6
Visitor, 1993 Mercury Topaz, 2.3L 4 Cylinder, 75,000 mi
Car runs good,1 out 10 won't start wait a couple of hours then starts.
ran fine this morning, went to start it this afternoon. cranks but will not start. I don't know enough about cars to know if its the fuel filter or what.