my 02' Silverado turns, but doesn't start. i changed the fuel pump last year and just replaced the fuel filter. It turns and almost starts but then stalls. installed new battery as well

Could be a fuel issue, should do a fuel bleed down test to see if there are leaking injectors. What size is this engine?

I'll have to see how to do do a fuel bleed. The pump is not factory, maybe it crapped out. Any ideas on how to check if the pump is the issue without having to remove the bed of the truck to access it?

Well yes of course. Just check the fuel pressure by hooking up the fuel pressure gauge to the Schrader Valve, turn the key to on position and let the fuel pressure build up. It should be 56 to 63 lbs. Then with the key off let it sit. The fuel pressure should not drop more than 5 lbs. in 3 minutes. But I need to know the size engine? There are several different engines for the 2500.

The engine is 6.0 . Thanks for your help! !