Assuming parts are good just because they're new can lead you waaaaaaaaaaay down the wrong rabbit hole. It's always best to verify, that way (to quote Marsellus Wallace) you know. You don't want to think, you want to know.
It doesn't have to be the pump, or the FPR. It can be other things too. Do you know for sure you aren't running the pulsator on the pump hanger and have the correct 30R10 piece of hose in it's place?
It might be a cheap fix once you get a replacement hose if that's the case.