12v or 24v
If its a 24v, it uses a Carter electric block mounted lift pump that are very prone to failure and performance is marginal at best. Your best bet is to replace it with something like a frame mounted FASS or Air Dog type fuel pump and do away with the block mounted pump.
Cummins part number is 4943048. That number may be superceded by now, but they should still be able to find it.
If its a 12v engine, it will use a mechanical type lift pump a bit different design.
Both pumps are around 100 bucks to replace depending on where you source it from.