I have been lucky in that of the four bricks I owned, all have had spotless tanks, including the fuel pump.
Having said that, if I had a tank that was gummed up with a lot of deposits, I would not hesitate to replace the fuel pump. Even if I could get it to run, I would not trust it because I have no idea of what wear and tear that crap could have done to the pump that may affect it's reliability.
My experience with injectors leads me to believe that even when you can get stuff to work, the process of cleaning to get ALL the stuff out can take many hours of run time. with pumps, that means a lot of hard work that can finally kill a pump.