how to check the valve timing modual

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Not familiar with a "valve timing module" in either a 2.3L 4 cylinder or 5.0L V8 Mustang in 1990. 20 years ago, valves did not have variable timing. If you are having extended cranks trying to start the vehicle, the best place to start (after doing basic visual checks under the hood) is to check base fuel pressure, and fuel pressure bleed down.