INDUSTRIAL INJECTION 436402 GM CP4 TO CP3 CONVERSION KIT — 2011–2016 LML 6.6L DURAMAX (WITHOUT PUMP)

Fix the LML CP4 weak link. The INDUSTRIAL INJECTION 436402 CP4-to-CP3 Conversion Kit adapts your 2011–2016 GM 6.6L Duramax LML to the proven Bosch CP3 architecture for dramatically improved reliability. This version is the components-only kit (no pump)—perfect if you already have a CP3 lined up.

Fitment

• 2011–2016 Chevy/GMC 2500HD/3500HD 6.6L Duramax LML
• Direct CP4.2 replacement with CP3 conversion hardware (tuning typically required for components-only kits)

What’s Included

• High-pressure pump adapter/brackets for CP3
• Hardware, lines/fittings, and conversion components for LML chassis
• Instructions
• Note: CP3 pump not included. Add an OEM-style or performance CP3 separately.

Why Convert?

• Reliability: CP3 design has a long track record in high-power Duramax builds.
• Protection: Helps avoid CP4.2 failure modes that can send debris through the entire fuel system.
• Scalability: Supports future fueling upgrades (lift pump, larger CP3, injectors).

Recommended Parts (CPP Internal Links)

• Prefer a kit with pump and no-tuning operation? INDUSTRIAL INJECTION 436401 (Includes CP3)
• S&S LML-CP3-CARB (With Pump) — 50-State CARB-Exempt, No Tuning
• S&S LML-CP3-NO-TUNING-REQ (With Pump) — No Tuning
• FLEECE FPE-LML-CP3-WP (With Pump)
• WEHRLI WCF100260 CP3 Conversion (Alt. brand)
• WEHRLI WCF100402 High-Pressure Line Upgrade (for big CP3s)
• Lift Pumps — All Duramax
• FLEECE PowerFlo In-Tank Lift Pump (2011–2016 LML)
• AirDog 4G/5G Fuel Systems (LML)
• Shop All GM Duramax Parts

Helpful Notes

• This no-pump kit typically requires custom ECM calibration on LML trucks to run a CP3 correctly.
• Emissions compliance varies by configuration. Check your local regulations before modifying emissions-controlled vehicles.
• Pairing a quality lift pump improves filtration, supply pressure, and CP3 longevity.

FAQ

No. Part 436402 is the components-only kit. If you want a complete solution with pump, see 436401 (includes pump) or the S&S and Fleece options above.

For components-only conversions on LML, tuning is typically required so the ECM properly controls a CP3 instead of a CP4. Kits that include a compliant harness/pump may avoid tuning, as noted on their product pages.

No—this components kit is not listed as CARB-exempt. For a 50-state option, see the S&S LML-CP3-CARB kit.

For stock to ~800 HP, the in-tank Fleece PowerFlo works great. For higher power or additional filtration/water separation, browse our Duramax lift pump options.