You can take the pump apart and look inside. You'll probably find rust particles and/or yellow ethanol goop clogging it up.
Then & Now Automotive sells rebuild kits or they will rebuild it for you.
I had a 1 year old Carquest pump fail and a brand new Carquest pump fail to pump ANY fuel straight out of the box.
Upon close examination, I discovered the pump arm was assembled incorrectly causing only part of it to make contact with the cam in the engine.
In any event, don't assume your new pump can't be the problem. Just about every new part is a product of Chinese slave labor and there is virtually no quality control.
