99 explore sport 4.0 L V6 Sohc...... would crank and start and run just fine now suddenly will crank but no start, replaced fuel filter and pump,...

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Have you checked for spark and fuel while cranking?

You will have to pinpoint what the engine is missing.

Spark

Fuel

Compression

All three of these are tested when the engine is being cranked over. There are two way of checking for fuel. Fuel pressure and injector pulse. Both are very important and must be present for the car to start. Fuel pressure is self explanatory. You just hook up the gauge and see what the reading is. Injector pulse is check with a noid light. The injector gets unplugged and the noid light gets plugged in to the injector clip. With the engine cranking over, this light must blink. This is the signal to the injectors from the computer. You can have all the fuel pressure in the world, but it wont matter if the injector is not pulsing gas into the cylinder like it should! All three tests play a very important part in diagnosing a no start condition. Be extremely careful when doing these tests. A simpler test would be to see if it runs on starting fluid. If it does, then you know you have spark and compression and you simply have a fuel delivery problem. Glad I can help. Please let me know if you have any further questions.

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