I just got the fuel pump, alternator, and starter replaced in my truck and it’s not starting. It will turn over for about 2 seconds then shut off. Brand new battery as well.

 

Welcome to the forum! By "turn over for about 2 seconds" do you mean the engine starts and runs for about 2 seconds before stalling or do you mean the starter will only spin the engine for about 2 seconds before no longer spinning the engine in an attempt to start? If you mean it starts and runs, have you checked the fuel pressure to make sure it's within specification, or have you checked to see if it will run if you feed it starting fluid? Do you have access to a noid light set to see if the injectors continue to get injector pulse?

-Rod