How do you know if the crankshaft position sensor is causing a no start?

What is your question?

The battery has been replaced as well as the starter, fuel pump and fuel pump modulator on my 1997 Infiniti Q45. But my car still only cranks but it won't start, just acts like it wants to. I've also tested the relays as well. The only codes that pulled up was for the modulator and a knock sensor code. Which way do I go now, I'm kind of at a loss.