1996 Plymouth Voyager Wont Start Up?

The first thing is to check the stored diagnostic fault codes. They will indicate the circuit that needs further diagnosis. What led you to replace the fuel pump? We know spark plugs aren't the problem because all four won't fail at once. The fuel filter will never solve that problem on a Chrysler product other than the diesel trucks.

Have you checked for spark when cranking the engine? Also check if the automatic shutdown (ASD) relay is turning on. It will turn on for one second when you turn the ignition switch on. What's important is whether it turns on again during cranking. It is if you have spark. If there's no spark, measure the voltage at any injector, ignition coil, or either small wire on the back of the alternator. All of those should have 12 volts during cranking.