FASS Drop-In Fuel Systems: No Hidden Costs. No Surprise Add-Ons.

Jake H • May 7, 2026

If you’ve spent any time shopping for a commercial truck air/vapor separation system, you’ve probably noticed something frustrating:

Some “bolt-in” systems on the market are expensive.

As in hundreds of dollars more expensive than they probably should be.

And sometimes it gets even worse.

At first glance, these "other" kits may appear similarly priced to a FASS Drop-In Series Fuel System—until installation day arrives and you suddenly realize you’re missing critical parts, fittings, adapters, fuel line, or mounting components that were never included in the box.

Now you’re:

Waiting on more parts
Spending hundreds more dollars
Prolonging truck downtime
Fighting unnecessary installation headaches

That’s exactly what we wanted to avoid when we developed the FASS Commercial Truck Drop-In Series Fuel Systems.

Built to Be Truly Ready to Install

Our engine-specific Drop-In Series Fuel Systems for:

…are designed to be exactly what they should be: Complete, bolt-in solutions right out of the box.

No hidden requirements. No surprise add-on kits. No “oh by the way, you also need this” moments halfway through installation.

When you open a FASS engine-specific Drop-In kit, it includes the components needed to install the system properly and get the truck back on the road.

Delivering ROI from Day One

FASS Diesel Fuel Systems are engineered to improve your bottom line, and the Drop-In Series is a shining example of that.

Our Drop-In Series systems are engineered to:

Improve fuel lubricity at LEAST 10% by removing air and vapor
Triple the life of injection components
Optimize MPG
Reduce soot output/regens
And more!

And unlike other fuel systems on the market, you won’t have to chase down extra parts just to finish the install.

The Universal Kit Exception

The only exception is our Universal Commercial Drop-In Series Fuel System.

Because it’s designed as a universal-fit solution for a wide variety of commercial diesel applications, some trucks may require:

Additional fittings
Extra fuel line
Minor adaptation components

That variability is simply the nature of a universal kit.

However, our engine-specific systems are a completely different story—they’re built to be as straightforward and complete as possible.

More Affordable Without Cutting Corners

The best part? Even while including the necessary installation components, FASS Commercial Drop-In Fuel Systems are still FAR less expensive than many competing bolt-in air/vapor separation systems.

You’re getting: