I have a 1997 Ford F-150 XLT and it won't start. The engine cranks over smoothly but it just won't ignite. I checked the spark but the test may have been faulty. I also ran a diagonsitics scan and found nothing. I checked all the crank sensor, the camshaft sensor, and the knock sensor and they were all fine. I performed a noid light test on the injectors but it didn't light. Could somebody help me please!!