If there’s one weak point on the 2011–2016 LML Duramax platform that diesel fans know all too well, it’s the CP4 high-pressure fuel pump.
And here at FASS Motorsports, we sell and install a TON of S&S Diesel Motorsport CP3 Conversion Kits because of it.
Honestly, at this point, the CP4 conversation has become unavoidable in the LML world.
The Problem: The LML CP4 Pump
The factory Bosch CP4.2 high-pressure fuel pump used on the LML Duramax has earned a reputation for one very unfortunate reason:
When it fails, it can take the entire injection system with it.
And unfortunately, that can mean:
- Injectors
- Fuel rails
- High-pressure lines
- Additional fuel system components
All contaminated and damaged by metal debris from the failed pump.
That repair bill can get ugly fast.
The Solution: Convert It to a CP3
This is where S&S Diesel Motorsport comes in. S&S developed one of the most trusted solutions in the diesel industry:
Replacing the factory CP4 with the proven CP3 high-pressure fuel pump.
The CP3 has long been known as a:
- Reliable
- Durable
- Proven high-pressure fuel pump platform
In other words, exactly what LML owners wish the truck came with from the factory.
50-State Legal CARB-Compliant Option
One reason we love S&S CP3 Conversion Kits is because S&S offers a 50-State Legal CARB-Compliant Kit—which features CARB EO #D-756-4.
This kit:
- Maintains factory emissions equipment
- Requires no tuning changes
- Includes all required hardware
- Allows owners to replace the problematic CP4 with a proven CP3 setup
That’s a huge deal for owners who want:
- Improved reliability
- OEM-style drivability
- Emissions compliance
Why We Recommend S&S Diesel Motorsport
S&S Diesel Motorsport has built a reputation as one of the absolute leaders in:
- Common-rail diesel injection technology
- Injection system engineering
- High-performance diesel components
The fitment, engineering, and overall quality of their CP3 conversion kits are top-tier.
Professional Installation at FASS Motorsports
We don’t just sell these kits—we install them all the time.
At our facility in Washington, Missouri*, we work on LML Duramax trucks regularly and have extensive experience with:
- CP3 conversions
- FASS Fuel Systems
- Diesel performance upgrades
Whether your truck is stock, lightly modified, or an all-out competition build, we can help you choose the right setup for your goals.
Serving Franklin County and Beyond
We proudly serve diesel owners from:
- Washington, MO
- Union
- Sullivan
- Pacific
- St. Louis area
- And all across Missouri
If you're thinking about ditching the problem-prone CP4 on your LML Duramax, we've got your back.
The Bottom Line
The factory CP4 pump is a known (and potentially catastrophic) issue with the LML Duramax.
That said, S&S Diesel CP3 Conversion Kits have completely solved that particular problem.
Better reliability, proven performance, and available 50-state legal compliance make these kits a no-brainer for LML owners.
Have questions? We're here to help.
- Phone: 636-429-7020
-
Email: info@fassmotorsports.com
FASS Motorsports
25 Town and Country Drive
Washington, MO 63090
