Yes, tank has the pump.
I recently had a rough idle and some black smoke when hard accelerating. I have 170,000 miles.
I used Hot Shot EDT 1oz and 10 oz of Marine Seafoam in a half tank of diesel, (premixed together and poured in) and it cleaned the injectors cause the rough idle left and no more black smoke in like less than 100 miles. What apparently happens besides wear, is the hot fuel carbons up inside injectors, and nozzles and you get rougher running due to stiction, the little parts inside do not move freely. I never had any start or power problems. My rougher idle was a feel it in the seat experience and developed over a couple of weeks.
I have bought some Hot Shot Extreme and will put that in next at 8 oz per 20 gallons, supposed to use every 6 months with Hotshot EDT 1 oz per tank. Doing it increases the cetane rating and the burn is hotter and more complete. So at cold engine starting it lights off faster.
Before replacing injectors, run some cleaner in and see if it improves. Black smoke is either excess fuel and or poor fuel atomization due to clogged injector nozzle holes, poor combustion. Clean working injectors increase the MPG