S&S Diesel Motorsport®, the world leader in common-rail diesel injection has developed a solution for CP4.2 high-pressure pump failures that have plagued the LML Duramax engine. The S&S solution is to remove the problem before it becomes a problem, by replacing the CP4.2 with a tried and true, bulletproof CP3 high pressure fuel pump.
CP4 high pressure pumps are the Achilles heel of the LML Duramax engine because of high failure rates, and commonly taking out the entire, very costly, high-pressure system with it (injectors, rails, lines). S&S Diesel Motorsport offers the first CARB-compliant (EO #D-756-4) 50 State CP3 conversion available for the LML. This includes all hardware necessary to replace the troublesome CP4 with a bulletproof CP3, requires no tuning changes, and still maintains factory emissions control equipment for $2,600 MAP.
S&S also offers two other versions of LML CP3 conversion kits for competition applications which don’t require after-treatment. One tuning required version for $1,780.00 MAP, and one drop-in no tuning required for $2,175.00 MAP.
Learn more about our 50 State Kit in this great tech article from Trailer Life Magazine
Learn more about CP4 failures and our 50 State solution from Diesel Power
Download Installation Instructions
FREQUENTLY ASKED QUESTIONS
This situation arises due to piezo injectors requiring back pressure to fire. If actual rail pressure is meeting commanded, it is recommended to either ensure fuel is getting to the return circuit or bumping shop air through the return to build the back pressure required for the injectors to start.
Once the injectors have fired off that initial time, there should not be any other instances where this happens. It only occurs upon the installation since the fuel system was opened up and air was introduced.
A lift pump is not needed when installing a CP3 on the LML. The CP3 has a gear pump on the back that draws suction from the tank. A lift pump is however beneficial in certain troubleshooting situations since it does supply pressure up the pump and any leaks would be external rather that sucking air. Lift pumps may also be beneficial in higher horsepower applications.
YES, this pump is designed to match the flow curve currently within the ECM even if the truck has been tuned already.
The biggest difference will be in the metering unit used on each product. With the No tuning required it will be using a custom metering unit that designed to match the flow curve of the CP4. The Tuning required pump will be using a LBZ based metering unit which will require a pump curve revision within the ECM.
Yes, if you are wanting to run one of our Duramax-based CP3s on a LML Duramax, we will allow you to buy our kit components as a kit paired with whichever size stroker pump you are needing.
The LML did not come from the factory with a lift pump, instead fuel from the tank is drawn to the pump via the gear pump on the high pressure fuel pump. In order for a DPK to work on a LML the fuel flow would need split at the gear pump. With that said, the R&D and overall cost of a DPK for the LML is quickly approaching the price of a CP3 conversion, which is the ultimate solution.
