1999 1500 Express van starts and shuts right back off

What is your question?

van starts and shuts right back off. changed the key ignition came up with code for security. changer fuel pump and a used spider fuel injectors with a new fuel regulator. Im thinking it needs to be relearned to the ecm....dont have a communication?

What makes this problem better or worse?

fuel only reads 40-45psi (3 pumps replaced)

How long has your 1999 Chevrolet Express 1500 had this problem?

4 months