In the earlier models of the Cummins B Series Engine, it was almost entirely mechanical including its fuel system. The fuel pump used in these engines was the P7100 injection pump, this pump is driven off the camshaft gear and drives it own internal camshaft to inject fuel to the individual injectors. This pump itself was one of the most popular options for fueling for the B Series Engines because of this simplistic design and how reliable it was. The P7100 injection pump also allows for large amounts of fuel to be delivered into the system with simple tweaking to the system to allow for larger injection events.