Diesel engines operate at higher compression ratios than gasoline engines, and fuel is injected under much higher pressure. An injection pump, usually driven by a belt or chain linked to the ...

Read more: 15 Popular Oil Filter Brands ... While DIY replacement of the CP4 injection pump and associated fuel system components is possible, I wouldn't exactly call it friendly.

Engines have evolved to meet changing emissions standards. One innovation from Cummins to meet those standards was the mechanical injection P-Pump.