Verified answer

check to see if there is a fuel pump prime relay.that sounds like your problem.

Sounds fishy. I would suspect for some reason, the fuel pump or the injection system is not running during the cranking mode of startup. You need to have a fuel pressure gauge check during starting, and also check the injector during starting. Was this truck starting before you changed all this stuff or did you spend all this time changing stuff trying to get it to start. I hope not. It's going to be something tricky, but probably very minor in nature.

you removed the fuel pump from the gas tank and put it into another blazer and then put it back in your blazer?...well if that's the way it is inspect the fuel pressure regulator