S&S CP3 Conversion Kit with Pump (50 State Legal)


$2,600.00 Includes Free Shipping.

WARNING: Cancer and Reproductive Harm - www.P65Warnings.Ca.Gov

S&S CP3 Conversion Kit with Pump

Fits 2011-2016 Chevy/GMC 2500/3500 HD LML


*50 State CARB Legal EO# D-756*

S&S Diesel Motorsport has come up with a solution to the CP4.2 high pressure pump failures that have plagued the LML Duramax Engine, this kit removes the problem before it becomes a problem. This kit replaces the CP4.2 with a tried and true, bulletproof CP3 high pressure fuel pump. The CP4 has been the Achilles heel of the LML Duramax platform because of the high failure rates and costly repairs. S&S Diesel offers the only CARB-compliant 50 state legal CP3 conversion available for the LML. This kit includes all the necessary hardware t replace the troublesome CP4 with a more reliable CP3, requires no tuning changes and still maintains factory emissions control equipment. DmaxStore has put together an additional installation kit that we use in house when replacing this that will include all gaskets and seals that should be replaced when doing this job. We also offer an optional compression fitting for the fuel pipe so you will not reuse the factory hose that can be prone to leak, see DmaxStore installation video below.

Now includes a smaller low-pressure supply line for factory fuel filter deletes, metering unit extension harness, and plastic mount for fuel temperature sensor.

No Recalibration is required, designed to work with vehicles that still retain the factory emissions control equipment. This product is California Legal and includes a CARB certificate with every order.


  • No calibration needed, direct drop in for stock truck

  • CARB compliant (EO #D-756)

  • Brand new latest generation Bosch CP3NH base

  • Metering unit extension (NEW)

  • Fuel temp sensor mount (NEW)

  • Extra supply line for factory fuel filter delete (NEW)


Why convert your LML's Fuel System from a CP4 to a CP3?

  • The stock CP4 is only capable of supporting up to ~500rwhp. A stock CP3 is capable of supporting 600+ rwhp in conjunction with the piezoelectric injectors. The reliable and proven S&S CP3 is capable of supporting nearly 850+ rwhp.

  • The CP4 was introduced as a cost reduction to the LML platform since a smaller amount of fuel is required when running the more efficient piezoelectric injectors. Since its introduction it has proven to be less reliable and less capable than the CP3 used in previous Duramax platforms.



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