08/28/2026
WHEN THE NOTORIOUS CP4 FAILS… UPGRADE IT. 🔧💪
One of our great customers loves their LML Duramax and wanted to keep it for the long haul. Unfortunately, a CP4 failure sent metallic contamination throughout the high-pressure fuel system.
Rather than installing another CP4, our customer chose to upgrade to a CP3.
The Stonehammer team completed a full high-pressure fuel system replacement — injectors, lines, etc. — along with a CP3 conversion, new FASS fuel system and custom AMDP tuning to bring it all together.
A substantial repair and a true team effort from start to finish. Huge credit to our crew, and a big thank you to our customer for continuing to trust our team with their Duramax!