It could be lot of things (seriously fuel pump is one of them) but you will need some tools and technical skill to diagnose it properly instead of guessing and throwing expensive parts at it until you are so frustrated you sell your beautiful Buell
No offense but I'll assume your skill is not much more than oil changes, because you went right to the forum to ask for guesses from strangers that have never seen your bike... instead of your toolbox
NO one here knows what's wrong with your bike
We will need you to help us diagnose it first.
May I suggest to at least download ECMDroid (free on google play) you will need to get a bluetooth dongle that lets it communicate wirelessly to your ECM. I like mine from Buelltooth.com
ECMDroid can tell you if it is running rich or lean, electrical problems, sensor problems, and yes install fuel tables as well. *Please DO NOT assume ECM 'tuning' is at fault and go down that rabbit hole!
You can also get a free .pdf download of the factory service manual from Buellmods.com or Buelltooth.com.
You will need a 50psi pressure gauge and a Buell specific 'tee' for the fuel line before you can test for fuel pressure. ECMDroid won't do that.
Or find a decent V-twin mechanic familiar with Buells or Sportsters.
Good luck buddy, I'll keep an eye out on this thread and help if I can