What Year Did Cummins Engines Have The P-Pump?

The second generation of 5.9L Cummins engine from 1994 to 1998 is one of the most desirable diesel engines – largely used in Dodge Rams — due to their power and durability. This is in part due to the Bosch P7100 inline mechanical injection, often referred to as the P-pump, which came to be in 1994 due to the new emission standards that went into effect that year, ensuring that the 5.9L Cummins could pass. Engines are often forced to be changed or discontinued, like the Ford 7.3L Power Stroke, to meet these ever-evolving standards. 

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Essentially, the P-pump cut down on the amount of particulate matter coming out of the engine’s tailpipe by using its six individual plungers to create higher fuel volumes and quicker injection rates. Each plunger would then pressurize fuel in separate barrels thanks to its internal camshaft, ensuring the fuel went to the correct injectors. This gave the P-pump fueling advantages over earlier models. Other changes to the Cummins to meet the emission standards included redesigned pistons with a narrowed ring land and a new fuel bowl with improved swirl, making combustion more complete. 

The P7100 injection pump works by compressing fuel with its rotating plungers. The injection rate and total lift of these plungers is controlled by a camshaft, which is rotated by a pump rack. The timing in which this fuel is delivered is critical while the vehicle is in motion if drivers want to avoid engine damage or failure — the right air to fuel ratio is super important, so the P-pump is focused on getting that precise amount of fuel. This will evenly transmit force in the cylinders to the torque converter as the P-pump manages the cylinder pressure by injecting fuel. 

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The P7100 injection pump keeps proper time to the engine by phasing pump port closure to a specific degree that coincides with the crankshaft angle. Even being one degree off will keep the engine from running its best. If the injection pump is not functioning to its best abilities, modifications focused on creating more horsepower will have no effect on the engine. 

With the success of the P7100 injection pump in the 5.9L Cummins engine and beyond, custom P-pumps have started popping up. These modded P-pumps can increase the engine’s cubic capacity and horsepower — by a lot — bringing the P-pump into the modern era.