Posted on 11/3/2025
The CP4 Pump: Your Diesel Engine's Ticking Time Bomb? The heart of your modern diesel truck is its high-pressure fuel injection system, and for many years, the Bosch CP4 pump was at the center of it all. Found in popular trucks from Ford, GM, and Ram, the CP4 was designed for efficiency. However, it has earned a notorious reputation for premature and catastrophic failure. Understanding why this happens and what you can do about it is crucial for any diesel owner. At Rochas Automotive, we've seen firsthand the damage a failed CP4 pump can cause. This guide will walk you through how the CP4 works, why it fails, and the practical steps you can take to protect your investment. What is a CP4 Injection Pump and How Does It Work? The CP4 high-pressure fuel pump has a critical job: it takes low-pressure fuel from the tank and pressurizes it to incredibly high levels (often over 30,000 PSI). This highly pressurized fuel is then delivered to the injectors, which spray a fine mist in ... read more