GM-GMC: 2000 Chev no start, fuel pressure gauge, theft deterrent system

Question
I have a 2000 Chev truck with a 5.3L,it cranks and runs only for a second than shuts off,I can hear the fuel punp run when the key is turned on.But still won't stay running

Answer
There are a couple of things that you can check.  The first is the fuel pressure.  You will need to put a fuel pressure gauge on it and see if you have adequate fuel pressure.  It may have enough to fire momentarily but not enough to keep it running. You should be looking for a pressure in the 65 psi range.  One more thing to check is if your theft light is flashing.  Some models were equipped with a theft deterrent system that would cause the concern that you have described.  If it is flashing, you will need to have it looked at by a technician with access to a scanner.
Hope this helps.