My oldest boys 01 1500 with the 5.2 will turn over for about 10-15 seconds before finally starting. This usually happens when it's started after a long time sitting. When it's warm it usually fires up right away. First thought is fuel pump but wanted to talk to the experts on here to see if I should check for anything else before dropping the fuel tank to replace the pump. Thanks for the help.

 

Next time you go out for a cold start (or, your son does....), cycle the key to on, but, don't crank the engine, the fuel pump will run for a few seconds. Do that at least twice, then crank the engine. If by doing that, it fires right up, the check valve in the fuel pressure regulator has failed. Rumor has it, that you can replace JUST the regulator, instead of doing the whole assembly.