FASS Drop-In Series Fuel System
For 2003 to 2024 Dodge/RAM, Cummins 5.9L & 6.6L
THIS IS NOT A LIFT PUMP! This is an air separation/filtration system that utilizes your factory lift pump.
Other Notes: 2003-2007 RAM 2500 & RAM 3500 5.9L Cummins (WITH AN IN-TANK LIFT PUMP). 2003-2004.5 trucks MUST have been retrofitted with an in-tank lift pump in order to utilize this product.
Installation of this kit on a cab and chassis may require modifications. Drop-In Fuel Systems are a plug-and-play filtration upgrade and are not compatible with our Fuel Sump Kit. No additional items are needed for installation. This plug-and-play filtration system retains the Cummins OEM in-tank fuel pump.
Overview
The FASS Drop-In Series Diesel Fuel System is engineered to be the most effective filtration solution for the 5.9L & 6.6L Cummins. Backed by a limited lifetime warranty, it protects your engine from issues caused by fuel contamination.
If you drive a Ram with a Cummins diesel engine and want better fuel filtration, improved reliability, and injector protection without adding an external frame-mounted pump, the FASS Drop-In Series Fuel System is the perfect solution.
Designed as a direct replacement for the factory engine fuel filter, the Drop-In Series delivers cleaner fuel, better water separation, and consistent fuel supply while retaining a factory-style installation. It’s ideal for stock and lightly modified trucks that demand long-term reliability without added complexity.
Key Benefits
Reliability, Simplicity, Protection: Engineered for long-term performance.
Supports Stock & Modified Cummins: Plenty of fuel for stock and modified GMCs and Chevrolets.
Injector Protection: Will triple the life of your injectors and injection pump.
FASS Filtration: Optimizes combustion, restores HP, maximizing MPG (results vary).
Limited Lifetime Warranty: Register your FASS system, and you’re covered.
Advanced In-Tank Filtration Technology
Water Separation: 3rd-party proven to eliminate over 99% of water.
Air/Vapor Removal: Eliminates entrained air and vapor that damages injection systems and reduces power/efficiency.
2 Micron Absolute Filtration – Microglass: Removes debris smaller than OEM filters can catch.
Mass Flow Return (MFR): Constantly “polishes” your diesel by sending unused fuel back through the filters, so your tank always holds clean, conditioned fuel.
Improves Reliability: Extends injection system life 3x.
Maximized Horsepower: Improved fuel atomization, restored injection timing, resulting in a more balanced engine.
Optimized MPG: More efficient/complete combustion (results will vary).
Peace of Mind: The Extreme Water Separator acts as a fail-safe in cases of extreme fuel contamination, preventing costly repairs and downtime.
Extreme Cold Weather Confidence: Dependable starts and operation in extreme cold, especially with the FASS Drop-In Fuel Heater Kit.
Cleaner Operation: Improved fuel quality and combustion reduces DPF regens and soot output.
Key Features
The only drop-in 5.9L & 6.6L Cummins filtration system that retains the full functionality of the water-in-fuel sensor!
The only drop-in 5.9L & 6.6L Cummins filtration system with air separation!
100% drop-in, no additional modifications needed.
Retains the factory in-tank lift pump.
Performance Radius Cuts (PRC): Smoother internal fuel flow, no sharp restrictions.
2-micron absolute filtration rating: Captures finer debris than OEM filters.
Removes over 99% of water from fuel (3rd party verified).
Patented FASS air/vapor removal process.
Electric heater options are available for improved cold weather reliability.
Limited Lifetime Warranty (with registration).
Why Choose FASS?
At FASS, we design fuel systems with longevity, reliability, and real-world use in mind. The Drop-In Series is engineered for diesel owners who want proven filtration technology and injector protection—without changing the character of their truck. It’s a smart, dependable upgrade for daily drivers and work trucks alike.
Vehicle Fitment by Year
Dodge/RAM Cummins 6.6L (application-specific fitment required)
Product Manual Downloads