How-To Prevent Disaster with a CP4 Fuel Bypass Kit | 6.7L Powerstroke

Did you know that the biggest fuel system weakness on the 2011-2021 6.7L Powerstroke is the fact that if the CP4 high pressure fuel pump has a roller lifter failure, the pump will explode and send metal shrapnel all throughout your entire fuel system before you can even react?

This is actually a commonly known problem with these pumps, and at this point I’m sure most owners of Super Dutys have heard of the infamous Bosch CP4 high pressure injection pump failure.

Of course, this absolutely decimates everything in the path, killing your expensive injectors and clogging every single passage, also ruining the high pressure rails and the fuel lines all in one shot. This get very pricey (to the tune of several thousands) and quick. The worst part? It can happen at any time, which means that it will most definitely happen at absolutely the most terrible time possible.

Is there a solution for 6.7L Powerstroke CP4 Failure?

Fortunately, there is actually a preventative step that you can take to keep a potential CP4 failure from being so expensive and destructive. The answer is a CP4 fuel bypass (aka disaster prevention) kit, and it is just about the perfect solution for this massive problem.

If you’ve already had the misfortune of experiencing a CP4 failure, well you have most certainly found out that it gets very expensive, really quickly. This is such a a common occurrence that Ford actually has a part number for all of the parts needed for a complete fuel system replacement. This tells me that they have run into contaminated fuel system often enough to make a special part number just for a kit to replace it. This fuel system replacement kit is Ford Part #EC3Z-9B246-A.

The Ford parts kit runs about 3k on a good day (core charges extra) and the labor time to perform the complete fuel system overhaul is 17 hours (as per the Ford factory service manual.) At dealer labor rates, that translates to about 5.5K, and that’s not even including the parts kit listed above.

This is what you’ll need to replace in a contaminated fuel system scenario if your pump lets go:

• New CP4 High Pressure Fuel Pump
• All the high pressure fuel lines mounted on the engine
• Both the primary and secondary fuel filters
• Both of the high pressure fuel rails
• All eight fuel injectors
• Low pressure fuel injector return hose assembly
• The fuel delivery pressure switch

Ouch. Makes the disaster prevention kit a very inexpensive value in comparison.

What is a 6.7L Disaster CP4 Prevention and Bypass Kit?

The kit is nothing short of a (power) stroke of genius. In essence, it takes the fuel pumping out of the bottom of the pump, and instead of sending it back through the entire system, it simply sends it right back into the fuel tank and filters, out of harms way. This keeps any potential metal debris from a high pressure fuel pump failure out of the rest of the system entirely.

Fun Fact: this CP4 failure is such a common occurrence that usually happens right around the 100,000 mile mark, that there is actually a class action lawsuit over the very issue of Bosch CP4 pumps failing.

Which is the best CP4 disaster prevention kit?

When it comes to a specialty product built to solve a specific problem, we usually would recommend the original developers of that product, especially if they pay as much attention to the design and ongoing development as the original disaster prevention kit makers at S&S Diesel do.

Hats off to their engineering department for the much appreciated features that they have evolved into this kit. We especially like that the fuel lines that with the kit are the factory Ford style quick-connect push lock fittings, It makes the install a total breeze, not having to worry about cutting and fitting custom lines, with the potential to introduce debris to the system from that process alone.

We are currently looking at the Gen2 Version of the bypass kit, which they have improved from the first version by a considerable amount, with one of the biggest new features being that they have extended the supply lines by an extra 25 inches away from the pump. This has the benefit of preventing the possibility that the CP4 pump failure clogs the fuel system with enough debris to back feed the resulting contaminated fuel back into the supply. The Gen1 (and the knockoff kits) were made in such a way that (in some cases) it is possible for the clogged system to overrun the fuel return and still send the metal debris back into the supply.

They’ve also thought of what happens when contaminated fuel is sent through their reroute kit, and have made a crucial upgrade to make dealing with a failure much, much easier. Normally, when a failure happens the fuel is bypassed as designed, keeping it from killing your expensive fuel system. The problem with the older kit and the knockoff is that this would still require a tank drop and a fuel system clean out, because the debris would be sent to the back. Still a much preferred option than replacing the entire fuel system, but also still somewhat of a pain.

They found that they could mount a filter in the return flow before it goes all the way back into the tank, preventing the contaminated fuel from ever making it’s way back to through the fuel lines to the tank and out through the lift pump. This makes cleaning up after a pump failure a much easier job. They incorporated a 2-micron filter into the design, that even has a clear bowl that can be checked instantly if you suspect a pump failure. If you need to replace the extra filter, they even sell that separately #6130120.

The best disaster prevention kit for 2011-14 models is this one here.

They make the new S&S Gen2 CP4.2 Bypass Kit for the 2015-2019 6.7L Powerstroke, and for those years you’ll want to make sure to buy part #7031190.

You’ll need a different kit for the 2020 and 2021 6.7L Super Duty trucks, as the layout of the lines have evolved somewhat on the newer models. You’ll want part #7032020 for these years.

How does this kit work?

The CP4 pump is internally lubricated by diesel fuel from the tank. After lubricating the crankcase area of the CP4 pump, fuel enters the high pressure pumping chambers and exits under pressure to the fuel rails and fuel injectors. The weakness of the CP4 pump lies in the crankcase area where a set of roller lifters ride on a camshaft. When the failure event occurs the lubricating fuel becomes contaminated immediately. Our bypass kit mounts to the CP4 pump and changes the routing of the fuel flow so that lubricating fuel from the crankcase is directed back to the fuel tank to be filtered before going through the fuel system again. Thus all fuel entering the pumping elements of the CP4 pump and leaving for the injectors is always routed through both of the vehicle’s fuel filters to eliminate any change of contamination from a high pressure pump failure.

Will this kit keep my high pressure fuel pump from failing?

No, the disaster prevention kit does not keep the pump itself from failing, it only protects the rest of your truck’s fuel system from the disaster waiting to happen. There are plenty of options to upgrade your Powerstroke’s pump and fuel system to less failure prone pumps, however that gets to be a pricier and much more involved option.

Aside from adding this bypass kit, the best thing you can do to prevent a CP4 pump failure in your truck is to use a fuel treatment additive to keep water and other contaminates from harming your pump and sending it down the road to imminent failure.

Does anything else need to be modified?

Nope, the bypass kit has been fully tested and certified. It doesn’t modify any fueling characteristics, and there is no performance benefit (other than keeping your wallet intact) so you wont have any trouble using it on a road legal truck. It can be added just fine to a fully stock truck with no other mods needed.

Conclusion

Has your Super Duty had a massive fuel system failure, or does the potential of a roller lifter pump failure stranding you (and your wallet) keep you up at night? Let us know your thoughts in the comments below, and as always, thanks for reading!