These BD Diesel lift pumps are designed to replace your stock lift pump. The stock lift pump is barely adequate for the stock engine, so when you start adding the latest in performance electronics or bolt-ons, it can soon be overwhelmed by fuel demand, placing additional strain on the injection pump.
It is designed to bypass/eliminate the use of the stock pump on the motor. The BD Diesel lift pump mounts directly on the frame rail with all the supplied hardware and wiring harness that plugs directly into your factory harness. The pump mounts directly on the frame because it's easier for the pump to push fuel rather than pull it from the tank and the vibrations from the motor shorten the life of the pump when it's mounted on the engine.
If your stock pump is still good and your just looking for a little added security you should look into the auxiliary Lift Pump Kit, you can add a proven second lift pump to ensure that your 1998.5-2002 VP44 or 2003-2007 CP3 pump has ample fuel to support over 600 horsepower! So don't be concerned about hard starts because BD's proprietary switch solves hard start issues common with other lift pump kits. Everything you need for a simple installation is included.