For diesel truck owners who want better performance, improved fuel economy, and protection for their injection systems, a FASS (Fuel Air Separation System) Diesel Fuel System is one of the best upgrades you can make.
With several models and flow rates available, picking the right system can feel overwhelming. This guide walks you through what matters most and how to choose the right FASS system for your truck.
Why Upgrade to a FASS System?
Stock diesel fuel systems often fall short in critical ways:
- They can allow air and vapor into the fuel, which reduces power, hurts fuel efficiency, and stresses engine components.
- Stock filtration often doesn’t clean fuel as thoroughly as it should — dirt, water, and debris can reach injectors and pumps.
A FASS system includes a high-volume fuel pump and a top-tier filtration setup that removes air/vapor, water, and debris (down to 2 microns) before the fuel reaches your engine. The result? Cleaner, steadier fuel delivery that leads to:
- Increased horsepower and torque
- Better fuel economy in many cases
- Longer life for injectors and the injection pump
- Smoother, quieter engine operation
Key Steps to Choosing the Right FASS System
Here’s what to consider when selecting your FASS:
- Identify Your Engine (Make, Model & Year)
FASS has dedicated solutions for most popular diesels:
- Ford Powerstroke (classic 7.3L up to modern 6.7L)
- Ram Cummins (5.9L 12-valve, 24-valve, 6.7L, etc.)
- Chevy/GMC Duramax (from LB7 through L5P)
2. Determine Your Horsepower / Flow Requirements
The flow rate (in gallons per hour, GPH) is a critical factor:
- Stock to ~600 HP: ~100 GPH
- ~600-900 HP: ~140-165 GPH
- ~900-1,200 HP: ~220-250 GPH
- Above 1,200 HP: 260-540 GPH
Even if you’re not running high horsepower now, if you plan future upgrades, it’s okay to choose a FASS system with a higher GPH than your current setup requires. The system delivers only what your engine demands.
3. Choose the Right Series / Kit Type
FASS offers multiple product lines depending on your needs, budget, and use case:
- Titanium Signature Series / Titanium Signature Series PLUS – The flagship line. Best for those who want top performance, whether daily use, towing, or competition.
- Drop-In Series – Uses the factory in-tank fuel pump; provides full filtration. Easier install, more budget-friendly. Ideal for stock or lightly modified trucks.
- Industrial Series – Built for heavy duty or continuous use: commercial trucks, farm equipment, construction, etc.
4. Reach Out When Unsure
If your vehicle is highly modified, or you’ve got unique demands (high altitude, odd fuel conditions, etc.), it’s smart to contact FASS tech support. They can give recommendations tuned to your setup.
Final Take
Choosing the right FASS Diesel Fuel System means matching your engine, horsepower, and how you use your truck to the correct GPH, series, and filtration level.
Do it right, and you’ll gain cleaner fuel, more reliable performance, and longer life for your injection components.
If you ever feel stuck deciding between options—or want to plan for future modifications—the experts at FASS are there to help. Better fuel protection leads to fewer problems down the road.
