Chances are it's the pump and if you're worried about it you'll likely want to fix it asap. I just don't like doing repairs and spending money until I'm sure about what's wrong. I never play "pin the tail on the diagnostic donkey".
Also-if the problem happens again before you get at it, you can try giving the bottom of the fuel tank a few taps while someone is trying to start the engine. If it starts-no more diagnostics are necessary, LOL. Careful not to dent or puncture the tank.

 

So I got a new pump, filter and relay. The filter and relay are not big deal. I have the filter off and the gas line run out to a gas can. If I could run the pump I could empy the tank. How do I manually run the pump?

 

Mever mind. I jumped the relay and drained the tank. I am going to drop the tank and put the new pump in.

 

Got it done. New pump, relay and filter. A few hours and it is all working just fine. Thanks for all you help.

 

WAIT WAIT WAIT. ok heres the poor mans fuel pressure guage. step 1 diagnose your problem. go get a cheap tire pressure guage that goes to 50psi. locate shrader valve on fuel rail. should be on the drivers side and have a black cap threaded onto it. cycle your key a few times and act as if your checking the tire pressure. look up the specs for your truck online. my bet would be like 35psi? but look to be sure. if the pressure is low replace your fuel filter and try again. see if the old one is plugged or dirty by blowing through it. if the pump is weak but still pumping you can often times jump the fuel pump relay under the hood. with your fuel filter unhooked place a bucket under the truck and jump the relay for the fuel pump. if the pump works it should almost empty the tank. Dont replace parts that arent the problem. DIAGNOSE!

 

A little late his symptoms are that of a bad fuel pump. Especially any high mileage vehicle its a smart choice to replace it. As pressure falls out the injection system has to work harder to make up the deficit. Stock fuel pressure at idle is 42-46.

 

and before he even checked the pressure you assumed automatically it was the pump. it could have been the relay or the filter itself. why would you replace parts before your positive thats the problem?

 

The symptoms pointed towards a pump and with the high miles I did not want to take a chance in getting stuck out in the middle of nowhere. I got lucky last time it went out, I was in town. I had just been about 2 hours out side of town though. If it went out while I was that far away the tow bill would have been as much as the parts. $205 for the pump, relay and filter. Not an expensive fix and the piece of mind is worth it.

 

You said you jumped the relay and the pump ran enough to empty the tank....could have been a plugged filter. but better safe than sorry. Just tryin to save you a few bucks.