Lift Pump Purpose - Diesel World

Today’s diesel engines use sophisticated extreme high-pressure fuel systems to increase performance and efficiency while promoting better emissions control and lower noise levels. The latest CP4.2 injection pumps and Piezo style injectors can be running 30,000+ psi and are extremely sensitive to getting only the highest quality ultra-low sulphur diesel possible. But whether you’re driving a brand-new 2018 model or a high-mileage, 20-year-old diesel truck, better protection for the fuel system is never a bad idea. The smallest particle or piece of debris in the fuel system can create a restriction, plug off ports or even scar and harm the internals of a pump or injector, so filtration and sufficient supply is key.


The Fuelab Velocity 200GPH fuel system uses a lightweight, high-flow, brushless DC motor to ensure long pump life, especially when used with today’s Ultra Low Sulfur Diesel fuels. The “wet motor” design means no seals to wear out, and an internal speed control with Pulse Width Modulated signal means volume and pressure can be set to precisely what each application requires.

Obviously, the OEMs aren’t going to overlook good filtration and their engineers have spent countless hours ensuring the fuel can be filtered properly and any water can be separated from it before it enters the injection system, but this doesn’t mean there isn’t room for improvement. In most applications, whether it be an all-stock truck or a heavily modified competition vehicle, the right high-performance lift pump system can offer multiple advantages. The Velocity pumps from Fuelab are one such system that not only adds additional filtration and water separation but will remove any trapped air in the system before fuel is sent to the injection pump and injectors. Removing air can quieten the engine, increase engine efficiency and extend the life of the small working pieces within the pumps and injectors. A lift pump can also feed positive fuel pressure at a larger volume to the injection pump, so for vehicles without a factory lift pump improved injection pump lifespan can be expected by taking some of the load off.


Most aftermarket lift pump kits will allow installation right inside the frame rail or outside the frame under the bed. The Velocity kit fits directly in front of the fuel tank on an easy-to-install, no-drill bracket. The pumps are mounted high enough that the base of the filter is barely visible, which keeps it tucked up clear of road debris.

In years past we’ve done plenty of testing on vehicles run with and without lift pump systems. In every instance the addition of a good lift pump lends some peace of mind and added support for more power potential. Years ago, in dyno testing a mildly built LB7 Duramax truck, we watched fuel rail pressure under hard load. In the mild performance tune (470 rwhp) rail pressure would hold steady around 22,000 psi, which is right at the values being called for in programming. However, in the max-performance tunes we watched rail pressure dip to 17,000 psi and the dyno numbers drop to under 450 hp. That 2002 Duramax platform wasn’t designed with a factory lift pump and the CP3 injection pump just couldn’t do that much work by itself. Power should’ve increased over the previous “smaller” tune, but when trying to pull fuel from the tank and pressurize it to 22,000 psi, it just couldn’t do it under that much demand. The addition of a 150 gph lift pump kit fixed all this. The engine not only ran quieter, it gained a significant amount of power on the large tune (554 rwhp). The pressure held at a constant 22K and the engine was back to performing as it should to its full potential.


Most pumps will supply a constant flow of fuel at steady pressure to the engine. Under low demand not all the fuel can be used by the engine, so a return to the tank has to be installed. Unused fuel is sent through a small hose back to the truck’s fuel fill neck to be recirculated in the tank.