I'm a little sketchy on your out-of-tank fuel pump. Not sure exactly what car you are talking about here... why you have an external fuel pump... etc...
Still... pumps making noises that change would might worry me. I don't know if you have a fuel pressure gauge and can monitor that, but I don't think I would risk things like fuel pumps. That's something that needs to work EVERY time... go into boost and that sucker decides to fail, you'll be getting a nice backfire and perhaps some leanout damage.
As far as if a pump is still working as long as it makes noise.. that depends on how the pump is designed...
It could make a noise and not pump a thing if the impeller inside decided to fail. Motor would just keep turning. Pump could go silent and engine could keep running. Won't run great, but it'll keep running.
So.. more info... but I'm not sure how confident I'd be with such a vital component to the car running and running safely.