LLY Duramax Fuel System

Ensure consistent rail pressure, protect your high-pressure injection components, and support serious horsepower gains on your 2004.5–2005 Chevy Silverado or GMC Sierra 2500HD/3500HD with our selection of LLY Duramax fuel system upgrades. The factory 6.6L LLY common-rail fuel system relies solely on the engine-mounted CP3 pump to draw fuel under vacuum from the tank, leaving the high-pressure system vulnerable to fuel starvation, cavitation, and premature injector wear—especially under heavy loads or when paired with performance tuning. Installing an aftermarket electric lift pump supplies a steady 8–10 PSI of positive fuel pressure while providing superior water separation and 2-micron filtration. For trucks demanding more fueling, we supply upgraded drop-in CP3 pumps, high-flow fuel injectors, fuel rail plug/shim kits, high-flow fuel supply lines, and billet tank sumps from industry-leading manufacturers like FASS Fuel Systems, AirDog, Bosch, Fleece Performance, and S&S Diesel Motorsport. Browse our complete inventory of LLY Duramax fuel system upgrades below to build a reliable, high-output fuel delivery setup.