We had our friends from S&S Diesel Motorsport® in-house at XDP to talk about one of the biggest headaches for Ford 6.7L Powerstroke owners: the dreaded CP4 failure. You’ve probably heard the stories: one minute your truck is running fine, the next your CP4 pump grenades and sends metal shavings through your fuel system. That “little” failure? It usually comes with a repair bill that can climb into five figures.
That’s why the S&S Diesel CP4 Disaster Prevention Bypass Kit exists. For a fraction of the cost of a fuel system repair, it keeps contaminated fuel out of your injectors and other components and prevents a pump failure from turning into a full-blown disaster. Let’s dig into what it is, why you need it, and how it works.
What is the CP4 Disaster Prevention Bypass Kit?
The CP4 Disaster Prevention Bypass Kit (aka CP4 bypass kit) is an insurance policy for your truck’s fuel system. When a CP4 pump fails, its internal components break down, sending fine metal debris through the fuel system. Without protection, those particles get sent through the injectors and rails, destroying everything in their path. If your pump fails with the bypass kit installed, the dirty or contaminated fuel is rerouted out through the return line and captured in a filter – leaving the rest of your high-pressure fuel system untouched.
In plain English: it helps keeps the expensive parts (injectors, rails, lines) safe from the contaminated fuel and limits the damage to the high-pressure pump itself.
Here’s What Comes in the Kit (CP4-6.7F-BP-G2.1):
- CNC-Machined Bypass Block And Hose Assembly
- Return Fuel Filter Assembly
- Return Fuel Filter Mounting Hardware
- Quick-Connect Fitting (For use with 2020+ models)
How’s it all work? In a stock CP4 pump, fuel flows through the case, then into the fuel system elements – injectors, rails, and lines. If the pump fails, that case fuel can carry metal-particle-laced fuel into the previously mentioned high-pressure elements, shutting your rig down. Sometimes this happens instantly, but in some cases, it occurs over time. The bypass kit blocks that case-to-pumping elements path. It forces the inlet metering valve to only draw clean, filtered fuel directly from the truck’s fuel filter.
Why You Need a CP4 Bypass Kit
- CP4 failure can be unpredictable. Some pumps can die under 10,000 miles; others can last half a million or more.
- If a CP4 fails, even the smallest amount of debris can contaminate your fuel system and all of the components in it.
- Repair costs are brutal. Without the protection of the bypass kit, replacing your injectors, rails, and pump can set you back up to five figures.
- The bypass kit is cheap insurance. It’s a small investment that can save you a ton down the road if your CP4 fails.
Does the CP4 Disaster Prevention Kit Really Work?
S&S Diesel says the latest Gen 2.1 CP4 bypass kit has had zero confirmed failures, as Justin states in the video at minute 3:30:
“…So, the original disaster prevention kit, we had a really high success rate. But there was a few failures or I guess you could say a few instances of it not containing all the fuel. The Gen 2.1 is perfect. We have not had a single report of it not working.”
S&S even intentionally destroyed a CP4 in their test truck to see what would happen. The result? Metal debris was caught in the return filter and clean fuel was still making it to the injectors.
Their test truck limped another 70 miles before it finally gave up. That’s proof the kit does exactly what it’s designed to do.
Are CP4 Failures Still Happening on Newer Trucks?
According to S&S, unfortunately yes. Even with updates in 2020 (like pinned lifter buckets to keep rollers from turning) newer Powerstroke trucks are still experiencing CP4 failures. The rate might be lower, but the problem hasn’t gone away.
As Justin states at 5:40 in the video,
“…they made an improvement in I believe 2020 with pinned buckets to keep the rollers from turning 90 degrees, but we still see failure modes of the buckets not turning, just the rollers skidding, and it just stops and makes metal that way, so I guess they did make some improvements to the newer trucks so the failure rate might be a little bit lower, but we still do see failures in the newer trucks”.
Can You Install the CP4 Bypass Kit Yourself?
If you’re a confident DIYer, you should be able to install the kit at home. Just remember: the high-pressure common-rail fuel system is extremely sensitive to contaminants. Even one speck of debris can cause problems.
If you aren’t comfortable doing the installation, it’s best to have a shop handle it. Proper installation is key to making your disaster prevention kit actually prevent disasters.
Filter Maintenance: How Often Should You Change It?
The CP4 bypass kit adds a return filter, but maintenance is simple:
- Change it with your factory fuel filter schedule.
- Inspect it for “glitter” or fine metal. In the video, you can see Justin from S&S point to the top of the filter for an initial check on the health of the CP4.
Pro Tip:
When you’re changing the fuel filter, don’t just swap the filter and toss it – cut it open and take a look inside.
Grab a filter cutting tool and cut the filter open. Pull the filter media apart and go through it looking for these warning signs:
- Glittery metal flakes: the classic “disco party” debris that means the pump is already chewing itself up.
- Fine, graphite-like dust: less obvious, but just as bad. These super tiny particles are another indicator of pump wear or failure.
The Bottom Line
A CP4 failure is one of the most dreaded problems for 6.7L Powerstroke owners. But thanks to our friends at S&S Diesel, the CP4 Disaster Prevention Bypass Kit gives you a simple, proven way to protect your F250/F350/F450/F550 Ford Super Duty.
Instead of facing a total fuel system replacement, you’re only replacing the pump and a return filter. Cheap insurance, real peace of mind.
Protect your truck. Protect your wallet. Get your CP4 Bypass Kit at XDP in case your high-pressure pump decides to call it quits.
Source:
“Why You Need a S&S CP4 Disaster Prevention Bypass Kit | XDP Q&A” YouTube, uploaded by XDP, August 13, 2025.
Image credits:
Image 1: S&S Diesel Gen 2.16.7L Powerstroke CP4 Bypass Kit, https://ssdiesel.com/wp-content/uploads/2018/08/SS-Gen2.1-Portrait.png
Image 2: S&S Diesel CP4 Disaster Prevention Kit, https://ssdiesel.com/wp-content/uploads/2018/08/CP4-Disaster-Prevention-Kit-How-it-Works-24APRIL2024.pdf