Product Description
Protect your L5P’s injection system with the FASS Drop-In Series Diesel Fuel System, engineered specifically for the 2020–2023 GM 6.6L Duramax L5P (Crew Cab Short Bed). This 100% drop-in assembly mounts in the OEM water separator location, maintains proper water-in-fuel (WIF) light and fuel heater functionality, removes entrained air, and filters particulates down to 2 microns to help prevent costly injector and pump failures.
Why it matters: Modern common-rail systems are extremely sensitive to water, air, and debris. By removing over 99% of water and fine contaminants, the Drop-In Series helps extend component life and deliver consistent fuel supply under load.
Key Features
- True drop-in design for L5P (no frame cutting or tank dropping required)
- Over 99% water separation and 2-micron particulate filtration
- Air/vapor separation to stabilize rail pressure
- Retains OEM WIF sensor and fuel heater functionality for proper alerts
- Backed by FASS limited lifetime warranty
Fitment
- 2020–2023 Chevrolet Silverado 2500/3500 HD, 6.6L Duramax L5P, Crew Cab Short Bed
- 2020–2023 GMC Sierra 2500/3500 HD, 6.6L Duramax L5P, Crew Cab Short Bed
Note: Designed to mount in the OEM water separator location. If you have an oversized/aftermarket fuel tank, verify there is adequate space for the Drop-In assembly before installation.
Cross-Reference / Related FASS Upgrades (CPP Diesel)
- FASS TSPC15250F220G – Titanium Signature Series Plus (2020–2023 GM 6.6L, 500–900 HP)
- FASS TSPC15180F140G – Titanium Signature Series Plus (2020–2023 GM 6.6L, Stock–500 HP)
- FASS DIFSL5P1001 – Drop-In Series (2017–2023 GM 6.6L L5P)
Installation Instructions
Visit FASS’s Installation Manuals page and search DIFSL5P2001 for the L5P Drop-In manual and resources.
Frequently Asked Questions
Will this system keep my OEM water-in-fuel light and fuel heater working?
Yes. The Drop-In Series for L5P is designed to utilize the OEM water separator so the WIF sensor remains on the “dirty side,” allowing proper detection and alerts. The design also retains the OEM heater functionality.
How fine does it filter and how much water does it remove?
The system filters to 2 microns and removes over 99% of water, helping protect sensitive injectors and the HP4 pump on the L5P.
Is it truly a drop-in for 2020–2023 L5P Crew Cab Short Bed?
Yes. It’s engineered as a 100% drop-in assembly for 2020–2023 L5P Crew Cab Short Bed trucks. Always verify clearance if you run a larger-than-stock fuel tank.
Specifications for Fass DIFSL5P2001
| Attribute | Value |
|---|---|
| Brand | FASS Fuel Systems |
| Part Number | DIFSL5P2001 |
| UPC | 850044137275 |
| GTIN | 00850044137275 |
| Engine Compatibility | 2020–2023 GM 6.6L Duramax L5P (Crew Cab Short Bed) |
| Filtration / Separation | 2-micron particulate; >99% water separation; air/vapor separation |
| Shipping Weight | 28 lb |
| Package Dimensions | 18 × 14 × 28 in |
| Warranty | FASS limited lifetime warranty |
| Prop 65 | WARNING: Cancer & Reproductive Harm – www.P65Warnings.ca.gov |
