Do you hear the pump prime up for about two seconds when you turn the key to Run
(not all the way to start)? If not, check for power to the pump (are you comfortable
around a volt meter?). If you do hear it prime, check your fuel pressure. Some auto
parts places have a fuel pressure gauge you can borrow or rent, or you can track
down an independent mechanic to check it for you.
Did your CEL ever come on? Most of the other things that might keep the truck
from running, like ignition/timing failure, would most likely throw a code.
How long ago did the previous owner replace the pump? Did they use an OEM pump,
used, or ? A co-worker just had the pump in his wife's minivan die after 10,000 miles.
He bought a cheap pump as a quick fix, and paid for it early. One day it worked, the next
it was dead.
If you have no power, check fuse, relay, wiring harness, plug, ground.
If you've got power, the pump whines, and you have no pressure, it's most likely the
pump. If you have power and the pump doesn't whine, it's most likely the pump.
Verify the fuel supply, and if it checks out OK, we can try to figure out where else to look.
If it cranks, then you need fuel and spark. Even if the mixture is wrong, you should
get something, even a sputter. You could verify spark with a quick hit of starter fluid.
Not much...shouldn't take much, and some of those are not good for sensors and such,
but if a quick hit of starter fluid gets the truck to run, you've got spark, so it's down
to fuel supply.