L5P Duramax FASS No-Drop Lift Pump Installation

Clean Fuel Without the Hassle

When it comes to protecting the high-pressure fuel system on an L5P Duramax, few upgrades offer as much peace of mind as a quality lift pump. Consistent fuel pressure, improved filtration, and air separation all contribute to a healthier fuel system, especially on trucks that tow, see higher mileage, or have performance modifications. For this installation, the crew at Miller Built Diesel equipped an L5P with a FASS Fuel Systems No-Drop Kit, simplifying what is often one of the most time-consuming portions of a lift pump install.

Anyone who has installed a lift pump on a late-model Duramax knows dropping the fuel tank can quickly turn a straightforward upgrade into an all-day project. Wrestling with a heavy tank, disconnecting factory fuel lines, and working around limited space underneath the truck can easily add hours to the job. The FASS No-Drop Kit changes that by eliminating much of the unnecessary work while maintaining a clean, professional installation.

The first step is gaining access to the bottom of the fuel tank. While many lift pump installations require removing and modifying the factory sending unit, this truck is receiving a FASS Sump Kit, eliminating the need to disturb any of the factory fuel system components. Since the sump mounts directly to the bottom of the tank, there’s no need to remove the sending unit or alter the factory pickup assembly.

Once the sump was installed and sealed, attention shifted to mounting the FASS Titanium Series lift pump assembly. Using the supplied brackets, Miller Built Diesel secured the pump to the frame rail in a protected location that still allows easy access for future filter service. From there, the fuel lines were routed from the newly installed sump to the lift pump and then forward to the engine. Care was taken to keep the lines away from exhaust components, suspension travel, and any sharp edges that could create issues down the road.

The electrical portion of the installation is just as important as the plumbing. The wiring harness was routed cleanly along the frame before being connected to the battery, ignition source, and pump. Keeping the wiring protected and secured ensures years of reliable operation while giving the completed installation an OEM quality appearance.

With everything connected, the system was ready to be primed. Cycling the ignition allowed the FASS pump to purge air from the lines before the engine was started. After confirming there were no leaks and verifying proper fuel delivery, the installation was complete and the truck was ready to hit the road.

While the simplified installation is certainly one of the biggest advantages of the No-Drop Kit, the long-term benefits are what make the upgrade worthwhile. The FASS system continuously filters fuel while removing entrained air and vapor before it reaches the factory high-pressure fuel pump. Delivering cleaner, more consistent fuel helps reduce unnecessary stress on expensive fuel system components, making it a valuable investment whether the truck spends its life towing, commuting, or making additional horsepower.

As this installation proves, upgrading an L5P with a FASS Fuel Systems No-Drop Kit doesn’t have to involve an all-day battle with the fuel tank. By utilizing the FASS Sump Kit and keeping the factory fuel components untouched, the job becomes faster, cleaner, and considerably more installer-friendly while delivering all of the performance and reliability benefits diesel owners have come to expect from a FASS Fuel Systems upgrade.