Quick Comparison
| Product | Best For | Est. Price | Rating |
|---|---|---|---|
| S and S Diesel Motorsport CP3 | Best Overall | ~$2499-$2999 | 4.7/5 |
| Industrial Injection CP3 Kit | Best Budget | ~$1899-$2299 | 4.6/5 |
| Exergy Performance CP3 | Best Premium | ~$2899-$3499 | 4.7/5 |
| Fleece Performance CP3 | Best for Duramax | ~$2199-$2799 | 4.5/5 |
| Dynomite Diesel CP3 | Best Compact | ~$1999-$2499 | 4.6/5 |
Intro
If you own a diesel truck with a Bosch CP4 injection pump, you are sitting on a ticking time bomb. The CP4’s precision engineering, while impressive on paper, makes it dangerously sensitive to real-world diesel fuel quality in North America. When it lets go, and many do, metal shrapnel contaminates injectors, fuel lines, rails, and the tank. The repair bill routinely tops $15,000.
The fix is a CP4 to CP3 conversion kit. The older Bosch CP3 pump is a proven workhorse with far looser tolerances, more forgiving fuel compatibility, and a track record of running hundreds of thousands of miles without issue. Diesel enthusiasts, fleet operators, and towing rigs across the country have made the switch, and the consensus is clear: the CP3 conversion is the single best insurance policy for a high-mileage diesel truck.
This guide breaks down the five best kits available in 2026, what to look for before you buy, and exactly what you are paying to avoid.
Top 5 Picks
1. S&S Diesel Motorsport CP3 Conversion Kit S&S is the benchmark in diesel fuel system conversions. Their kit is precision-machined in the USA, includes a high-quality CP3 pump, all necessary fittings and lines, and comes with detailed installation documentation. It is the most popular choice among serious diesel mechanics for good reason. fitment is exact, and the pump is rated for stock and modified applications.
2. Fleece Performance Engineering FPE-CP3K Fleece Performance has built a strong reputation in the Duramax and Cummins communities. Their CP3 conversion kit is fully plug-and-play for LML Duramax applications and includes a performance-spec CP3 pump capable of supporting higher horsepower builds. An excellent pick if you plan to tune your truck after the conversion.
3. Industrial Injection CP3 Conversion Kit Industrial Injection’s kit is a well-priced entry point that does not cut corners. It ships with a remanufactured CP3 pump, new seals, and all hardware. For a stock daily driver that just needs CP4 risk eliminated, this is a reliable, cost-effective solution that gets the job done.
4. PPEI Power Performance Enterprises Kit PPEI combines their tuning expertise with a clean conversion package. Their kit pairs particularly well with their own EFILive tunes, making it a strong choice for truck owners who want to do both the conversion and an ECM tune at the same time.
5. Oregon Fuel Injection OFI Conversion Kit OFI has been rebuilding and supplying diesel fuel injection components for decades. Their CP3 conversion kit is methodically assembled using tested pump cores and precision fittings. A trusted option for fleet managers and shop owners who need consistent, repeatable quality across multiple vehicles.
What to Look For
Pump quality and sourcing. Some kits include remanufactured pumps, others new units. Understand what you are getting. Remanufactured pumps from reputable shops are perfectly acceptable; no-name imports are not.
Compatibility with your exact application. CP3 kits are application-specific. Confirm the kit is built for your model year and engine code. LML, LGH, 6.7 Power Stroke, etc.
Hardware completeness. A good kit should include the pump, all mounting hardware, fuel lines, fittings, and a return line kit. Buying missing pieces separately adds cost and delays.
Tune requirement. Some trucks require an ECM tune after the CP3 conversion for optimal fueling. Factor that into your total project cost.
Warranty. Reputable brands back their conversion kits with at least a one-year warranty on the pump and components.
Final Thoughts
The CP4 to CP3 conversion is not a glamour upgrade. it is damage prevention. If you own an affected diesel truck and plan to keep it for another 100,000 miles, the math is straightforward. A quality conversion kit costs a fraction of what a CP4 failure will cost you in parts and labor. The five kits above represent the top of the market in 2026. Go with a name-brand kit from a diesel-specialist shop, confirm your application, and get the job done before the pump decides to do it for you.
Frequently asked questions
Why is the CP4 pump considered a failure risk on diesel trucks?+
The Bosch CP4 high-pressure fuel injection pump uses tight metal-on-metal tolerances that depend on diesel fuel for lubrication. U.S. diesel can contain up to 15% biodiesel blends, which reduces lubricity. When the pump fails, metal fragments contaminate the entire fuel system, turning a $1,500 pump into a $10,000-$20,000 repair bill.
What trucks are most commonly affected by CP4 failures?+
The CP4 pump was used in 2011-2016 Ford 6.7L Power Stroke trucks, 2011-2016 GM Duramax LML engines, and several Ram EcoDiesel models. These platforms see the highest failure rates and are the primary candidates for a CP4 to CP3 conversion kit upgrade.
Will a CP4 to CP3 conversion void my truck's warranty?+
Installing an aftermarket fuel system conversion on a truck still under warranty can affect powertrain warranty coverage. If your truck is out of warranty, there is no concern. Always check with your dealer or review the Magnuson-Moss Warranty Act to understand your specific situation before modifying a warrantied vehicle.