The lift pump is a diesel fuel supply pump that delivers fuel from the fuel tank up to the engine's injection system. Almost all diesel engines have a lift pump of some sort, from the old mechanical injection systems to newer high-pressure common-rail rigs.
The lift pump is used on many diesel engines to transfer fuel from the fuel tank to the fuel injection pump. The lift pump runs at all times when the key is on, and many OEM lift pumps have a short life span due to this duty cycle. Your injection pump cannot supply the proper pressure and/or lubrication required without the proper fuel supply. When the lift pump fails, the injection pump will continue to draw fuel through the lift pump under a vacuum. Normally you can tell little or no difference in the engine operation when this happens. The injection pump will eventually be unable to meet the engine ECM's fuel demand, causing the engine to derate and feel extremely underpowered. At this time, the injection pump will either need to be rebuilt or replaced.
These FASS Dura-Max Flow Enhancer pusher pumps were designed after the FASS DDRP series lift pumps. And is now available for the GM and Chevy Duramax diesel engines. GM trucks equipped with the 6.6L Duramax do not have a stock lift pump, forcing the injection pump to "pull" the fuel all the way from the tank, creating a vacuum, and constantly introducing more air and vapor into your fuel. The Dura-Max Flow Enhancer creates a positive fuel flow, "pushing" it to your injection pump, eliminating vacuum, and drastically reducing air and vapor in your fuel.
NOTE: Only The AirDog FRRP-100 and FRRP-150 Dodge Diesel Lift Pumps can support a 5.9L Cummins engine with increased power levels.