Fleece FPE-LML-CP3-10 CP3 Conversion Kit with Heavy-Duty CP3 | 2011-2016 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax LML

Features:

• Replaces failure-prone CP4 with reliable CP3
• Includes heavy-duty 10mm CP3 pump
• Improves fuel system reliability and longevity
• Supports stock and aftermarket fuel systems
• High-flow CP3 feed and return fittings
• Preformed molded fuel lines for clean install
• OEM-style fit and finish
• Compatible with lift pump setups
• Includes all necessary hardware and fittings
• FCA extension harness included
• SC-E emissions certified

High-Performance CP3 Conversion Kit for 6.6L Duramax LML

If you’ve owned an LML Duramax long enough, you've probably heard the horror stories about CP4 failures—and they’re not exaggerated. The factory CP4 injection pump, introduced on 2011–2016 Silverado and Sierra 2500HD/3500HD trucks, has earned a reputation for being both underpowered and unreliable. When it fails, it often takes the entire fuel system with it, leaving you with a huge repair bill and a truck stuck in the shop. That’s where the Fleece CP3 Conversion Kit with Heavy-Duty CP3 comes in. This kit lets you ditch the CP4 and replace it with a brand-new Bosch CP3 pump—the proven workhorse used on earlier Duramax models. But this isn’t just a stock CP3. Fleece includes a 10mm stroke cam for increased fuel output, giving you better fueling capability and improved reliability whether your truck is stock or tuned. It’s built to handle more power and heavier workloads without the risk of catastrophic failure that comes with the CP4.

High-Quality Hardware for Straightforward Install

Everything about this kit is designed for clean, functional installation. It includes preformed fuel feed and return hoses, so you’re not stuck trying to make universal lines fit. The high-flow CP3 fittings help reduce restriction and keep fuel delivery consistent, even under demanding conditions. Fleece also includes their valley feed line, making this kit compatible with aftermarket lift pumps if you decide to upgrade later. The kit comes complete with the CP3-to-rail high-pressure line, mounting adapter, dosing injector lines, an FCA extension harness, and all the hardware you’ll need. Fitment is clean, with OEM-style quality and finish throughout, so it won’t look out of place in your engine bay. Behind the wheel, you’ll notice smoother throttle response, more consistent power delivery, and peace of mind knowing your fuel system isn’t a ticking time bomb.

Fits: 2011, 2012, 2013, 2014, 2015, 2016 GM 6.6L Duramax LML

Application Notes:

• This kit has been tested for use in stock application trucks that did not utilize a fuel lift pump. For optimal performance, if the truck is equipped with a lift pump, the feed pressure to the CP3 should not exceed 2 psi. Engine surging may be induced by the additional fuel pressure of a lift pump operating at pressures over 2 psi. If you are intending to combine this kit with a Fleece PowerFlo lift pump, contact us for a lower rate spring for your pump to accommodate operation with this kit. For higher lift pump pressures, FCA table values will require adjustment.
• Covered under SC-E Emissions certificate #: SC-FLC01-0013
• This kit does not use a PowerFlo 750. This pump is available separately Here.

Kit Includes:

• CP3 to rail high pressure fuel line
• High flow CP3 feed and return fuel fittings
• Preformed fuel feed and return fuel hoses
• CP3 mounting adapter
• Dosing injector distribution block, feed and return linesFCA extension harness
• low pressure fuel feed line
• Hardware kit

Install Instructions