Fuel Pump problems...

How can u tell when a fuel pump is going out on a vehicle?

I assume it is a TBI system. Here is a site explaining fuel pressure testing:
http://www.autozone.com/az/cds/en_us/0900823d/80/08/73/10/0900823d80087310/repairInfoPages.htm

What are the problematic symptoms?

What year is it and what is it doing?If the fuel pump,get one from the dealer or a Carquest Parts store.They are both made by Delphi whom is GM's supplier of their fuel pumps and Carquest switched to them ditching Airtex.

If you need to replace this pump Do yourself a huge favor and pull the bed. Its only 8 bolts ,three screws on the filler neck and a couple of plus for the lights. Also inspect the brake lines while its off. The bolts may be locktiteed in and be a little tough to get out. But if you are doing this work on the ground it is well worth the time to pull the bed. In the end it will save you hours of work and you will know its done correctly.

When I start my truck up, it turns over for a while then it starts, I did hear from some people that it could be the fuel pump itself..if that isn't it, then what else would it be?