Upgrade the fuel delivery on your 5.9L Cummins with the Fleece Performance CP3K for 5.9L Cummins (CUMM-CP3K-5.9). This is a purpose-built modification that repurposes a 6.7L CP3 core to eliminate the factory fuel flow restriction that kicks in around 3,000 RPM, a common pain point for stock CP3 setups on engines used beyond stock power levels.

Why this matters: when you push past 3,000 RPM, a stock CP3 can lose fuel flow and rail pressure, leading to a noticeable dip in horsepower right when you’re demanding peak performance. The CP3K maintains consistent fuel rail pressure across the entire RPM range, ensuring your Cummins can respond with clean, reliable power when you need it most—whether you’re towing heavy, accelerating out of a corner, or chasing peak power on the track.

What’s in the kit

• Brand new 6.7L Cummins CP3 pump
• 1/2" CP3 feed fitting
• 3/8" CP3 feed fitting
• 6.7L CP3 to 5.9 high-pressure rail line
• 3/8" fuel line and hose clamps
• Brand-new Bosch CP3 core with no core charge

Key benefits that set CP3K apart

• Consistent fuel rail pressure across the full RPM range, reducing horsepower loss at higher engine speeds.
• Direct, bolt-in upgrade designed to integrate with the 5.9L Cummins platform without extensive fabrication.
• Improved fuel flow compared to a stock CP3, enabling more reliable performance under boost, load, and hard acceleration.
• Quality you can trust with a brand-new Bosch CP3 component and a purpose-built connection to the 5.9L rail.
• No core charge and a straightforward warranty path for peace of mind.

Ideal for

• 2003–2007 Dodge Ram 2500/3500 5.9L 24V Cummins owners looking to unlock higher RPM performance
• Diesel enthusiasts seeking dependable fuel delivery during towing, hauling, or off-road use
• Builders and racers who want a reliable upgrade path without replacing the entire fuel system

Practical considerations and tips

• The CP3K is designed to replace the stock CP3 with minimal modification, delivering a seamless upgrade in fuel delivery.
• Pairing this upgrade with supporting fuel and air handling improvements can maximize the benefits, especially under boost or heavy load.
• Install with attention to the new feed fittings and high-pressure rail line connections to ensure consistent sealing and pressure delivery.

Warranty includes a 1-year limited parts warranty for confidence in your investment.

With the Fleece Performance CP3K for 5.9L Cummins, you’re choosing a targeted, performance-driven solution that addresses the specific RPM-related fuel flow limitation of the 5.9L platform. It’s the practical upgrade for drivers who demand consistent power from redline to highway, without the guesswork of how your fuel system will respond under real-world driving conditions.