how long had the truck been sitting ? gas in the tank could of gone bad and killed the fuel pump..
turn the key in the On position a few times, then off... and then find a place under the hood near
the motor you can crack open the fuel line. You are checking the pressure of course. and if gas
comes out, how bad does it smell ?
Also you can spray some starting fluid into the air intake while cranking it too..
if it fires for a few seconds, ..then its fuel related. If still nothing, prob spark related...
check sparks easy... pull off a coil pack and check for spark that way.