Start with Your Truck’s Age and Mileage

One of the first things to consider is how old your truck is and how many miles are on it.

• Newer, lower-mileage trucks often still have a healthy factory in-tank fuel pump.
• Older or higher-mileage trucks may have fuel pumps that are already worn or nearing the end of their service life.
  
  

If your truck is newer and the factory pump is still strong, you may not need a full replacement lift pump system right away. Instead, focusing on fuel filtration and air/vapor separation can provide tremendous protection.

Consider Your Performance Modifications (and Future Plans)

Your current setup—and what you plan to do in the future—plays a major role in selecting the right FASS system.

Answer these questions:

• Is the truck completely stock?
• Is it lightly modified with tuning or intake/exhaust upgrades?
• Do you plan to add larger injectors, turbos, or more aggressive tuning later?
  
  

If your truck is stock or lightly modified, you may not need additional fuel flow beyond what the factory pump provides. However, if you’re planning significant performance upgrades, choosing a higher-capacity FASS system now can save time and money later.

How Long Do You Plan to Keep the Truck?

This is one of the most overlooked—but most important—questions.

If you plan to:

• Keep the truck long term
• Rely on it for towing, work, or daily driving
• Avoid costly injector or injection pump failures
  
  

Then investing in proper fuel filtration early makes a lot of sense. Clean, air-free fuel can extend injection system life by up to three times, making a FASS system one of the smartest long-term reliability upgrades you can make.

When the FASS Drop-In Series Is the Right Choice

For many diesel owners, the FASS Drop-In Series Fuel System is the perfect solution. The Drop-In Series is ideal for stock and lightly modified trucks, including:

• Cummins (2003–2024)
• Duramax (2017+)
• Powerstroke (2017+)
  
  

These systems are designed to provide full FASS filtration and air/vapor separation while continuing to use the factory in-tank fuel pump for fuel flow.

Benefits of the FASS Drop-In Series include:

• 2-micron absolute filtration
• Removal of air, vapor, and over 99% of water
• Improved fuel lubricity
• Extended injector and pump life
• Simple, bolt-in installation using factory mounting locations
  
  

For trucks that don’t need increased fuel flow but still require maximum fuel protection, the Drop-In Series offers an outstanding balance of simplicity, performance, and reliability.

When a Full FASS Fuel System Makes Sense

If your truck has:

• High mileage
• Performance upgrades that increase fuel demand
• Plans for future horsepower gains
• A factory pump you don’t want to rely on long term
  
  

Then a full FASS Fuel System (Titanium Signature Series or Titanium Signature Series PLUS) with its own dedicated lift pump may be the better option. These systems not only provide the same advanced filtration as the Drop-In Series, but also ensure consistent fuel pressure and volume under all driving conditions.

The Bottom Line

Determining which FASS Diesel Fuel System you need comes down to understanding how you use your truck today—and how you plan to use it tomorrow.

Newer, stock or lightly modified trucks often do great with the FASS Drop-In Series. Higher-mileage or performance-focused trucks may benefit from a complete FASS lift pump system.

If you’re ever unsure, the best next step is to contact our customer service team. Our experts can help match the right system to your truck, your goals, and your budget—so you get the protection and performance you need without overbuying!