If there is one downside to the 6.7 Powerstroke, it was Ford’s decision to use the Bosch CP4.2 high-pressure fuel pump. The CP4.2 is notorious for failing early, and it also struggles to adequately fuel past 500 horsepower. A much better option is the Bosch CP3 fuel pump.
For those looking to push their builds to the next level performance-wise, a performance a CP3 conversion on your 6.7 Powerstroke is a must. In this guide we’ll discuss the problems with the CP4.2, the benefits of switching to the CP3, and discuss how to do the conversion.
Why the CP4.2 is So Bad
There are two main problems with the CP4.2: reliability and inadequate fuel flow past 500 horsepower. The CP4.2 is prone to premature failure. There have been many complaints about the pump failing on completely stock trucks, and the problems only increase on those that have been modified.
The stock system is actually considered unreliable enough that brands have developed disaster prevention kits. These come into play when the CP4.2 fails, and stops debris traveling through to the injectors and destroying the rest of the system. It’s a must have for any 6.7 Powerstroke, especially those that are modified, as a CP4.2 failure can lead to around $10,000 in repairs.
In addition, the CP4.2 fails to supply enough fuel on builds that surpass 500-550 wheel-horsepower. It just cannot keep up with fuel, causing the engine to run lean and potentially detonate and incur catastrophic damage. If you plan on surpassing more than 500-550 wheel-horsepower, you absolutely need to upgrade from just the stock CP4.2.
When to Consider Ditching the CP4.2
For the most part, the time to do a 6.7 PowerStroke CP3 conversion is if you plan on heavily modifying your engine. On stock vehicles, even though the pump is unreliable, you’re better off getting the S&S Diesel disaster prevention kit. This is a much cheaper option and will prevent catastrophic damage if the pump breaks.
Considering that the newer 6.7 PowerStroke diesels produce around 400-450 wheel-horsepower stock, there is not a ton of room to modify before you need to start upgrading the fueling. If you just plan on throwing on an intake or something small, the stock fuel system will be adequate. However, if you want to engage in tuning or are even considering a turbo swap, you’ll definitely want the 6.7 PowerStroke CP3 conversion as an option.
How to do a Ford 6.7 PowerStroke CP3 Conversion
The term “conversion” is a bit misleading, because you are not actually replacing the CP4.2 pump. Instead, you are adding the Bosch CP3 pump so you can run both of them together as supplemental pumps. Those familiar with the Cummins and Duramax platform are familiar with the Bosch CP3, as it’s what they use stock.
Adding the CP3 on top of the CP4.2 will greatly increase the PowerStroke engine’s fueling capacity. With both pumps together, the PowerStroke can fuel enough for an incredible 900 wheel-horsepower. That’s almost double what the stock fuel system can handle, and it does not sacrifice reliability. The Bosh CP3 is widely considered much more reliable than the CP4.2, so you are not sacrificing anything by adding it.
By far, the most popular 6.7 PowerStroke CP3 conversion kit is the HS Motorsports Dual High Pressure Fuel Kit. HS uses a brand new CP3 fuel pump and includes all necessary pieces for installation, including a new pulley, serpentine belt, hardware, harness, and fuel filter. Installation is not the easiest, and will probably require a qualified mechanic to ensure everything fits properly.
In addition to the Dual High Pressure Fuel Kit, HS also recommends using either a lift pump or their low-pressure fuel system to ensure proper filtration and water-separation. This is not necessary, but is a smart step to take when adding the kit.
After installation you are good to start really turning up the wick on your 6.7 PowerStroke build. If the stock CP4.2 and CP3 combo still does not flow enough for your needs, you can also use the 6.7 Cummins 10MM stroker pumps to exceed 1,000 horsepower.
Alternatives to a CP3 Conversion
For those looking for alternatives to a 6.7 PowerStroke CP3 conversion there are a few options. One of the most popular is the S&S Diesel CP4 to DCR Pump conversion. This replaces the CP4.2 with a DCR replacement high-pressure fuel pump. It outflows the CP4.2 by 25%, meaning it is capable of sustaining a little bit more power. This is a great option for those worried about the reliability of the OEM pump but aren’t necessarily looking to add lots of power through mods.
The next best option is to use a stroker version of the CP4.2 pump. This is an upgraded CP4.2 that can outflow the OEM pump. The Exergy 10mm Stroker Scorpion CP4.2 is a direct bolt-in for the OEM pump, and can support more than 800 wheel-horsepower, about 300 wheel-horsepower more than stock.
While you can replace the CP4.2 with a CP3, the better option is to go with a dual fuel kit. A dual fuel kit adds a supplemental CP3 pump to the OEM CP4.2 system, giving you the best of both worlds.
If you plan on doing a 6.7 PowerStroke CP3 conversion, you will want to have a tuning option set up. After all, there is no point upgrading to the CP3 unless you plan on adding lots of horsepower.
The Bosch CP3 high-pressure fuel pump is much more reliable than the CP4.2 fuel pump. It delivers solid performance but has been proven to last much longer.