S&S Diesel CP4 disaster prevention kit for 6.7 Powerstroke
Oct 21 2026

Will My 6.7 Powerstroke CP4 Fail? CP4.2 Failure, Disaster Prevention Kits vs. DCR Conversion

If you own a 6.7L Powerstroke, you have probably heard about the CP4. It is the most talked-about weak point on this engine. It comes up in nearly every “common problems” list and in a steady stream of forum threads. This post covers what the pump is, how it fails, the warning signs, and the two most common ways owners protect themselves: a disaster prevention kit (DPK) or a DCR pump conversion.

Which 6.7 Powerstroke Trucks Have the CP4.2?

The Bosch CP4.2 is the high-pressure fuel pump on the 6.7L Powerstroke. S&S Diesel Motorsport describes it as the pump “in every 2011+ 6.7L Power Stroke.” S&S builds both its DPK and DCR conversion to fit 2011 and newer Super Duty trucks.

Ford did change pump configurations between generations. If you are buying a replacement pump or a protection kit, confirm fitment with your VIN, your production date and the pump that is actually installed on your truck. It is also worth checking your VIN for open recalls or service campaigns before you spend money.

How a CP4.2 Fails

The mechanical failure

The CP4.2 is lubricated by the diesel fuel passing through it. S&S explains the known failure this way: the pump’s roller lifters can rotate on the cam lobe, so they skid and grind instead of rolling. MotorTrend describes it as metal-on-metal contact that air inside the pump makes worse.

Why it matters: debris

The pump itself is not the expensive part of a failure. The problem is where the metal goes. In the stock setup, debris from a failing CP4 can travel into the injectors, fuel rails, lines and pressure regulators. That is why a pump failure often becomes a complete fuel system replacement.

What raises the risk

Ford’s 6.7L fuel system service job aid lists the contaminants that cause premature pump and injector wear and metal debris:

  • Water: reduces lubrication and can rust or corrode the pump’s machined surfaces.
  • DEF in the fuel tank: causes wear, corrosion and plugged injector return lines.
  • Gasoline, ethanol, kerosene or incorrect additives: cause wear, debris and fuel knock.
  • Biodiesel blends above 20%: cause wear, corrosion and filter gelling.
  • Lack of filter maintenance: causes low supply pressure and hard starts.

The supply side also matters. The 6.7L watches low-side fuel pressure and will warn you and derate the engine if it sees low pressure. Industry write-ups note that the CP4 is especially sensitive to insufficient supply pressure. Restricted filters, a weak supply pump, air leaks and running the tank dry can all starve the pump.

You will see “U.S. diesel has poor lubricity” repeated a lot. Treat it with some care. U.S. diesel spec (ASTM D975) does include a lubricity requirement. The bigger, controllable risks are water, contamination, starvation and neglected filters.

CP4 Failure Symptoms

Ford’s service job aid lists these symptoms of fuel contamination damage:

  • Crank, no start
  • Long crank or hard start
  • Rough running
  • Reduced power
  • Engine knocking
  • Exhaust smoke
  • Fuel rail pressure slow to build

Codes are not a diagnosis

A low rail pressure code such as P0087 means rail pressure is lower than commanded. It does not tell you whether the problem is before, inside or after the high-pressure pump. A clogged filter, weak supply pump, air in the fuel or a leaking injector can set the same code.

Proper diagnosis checks low-side supply pressure first, then compares commanded and actual rail pressure. Ford’s guidance is that metal debris found at the pump’s control valve or in the high-pressure system means the complete high-pressure system needs replacement, not just the pump.

If you suspect a misfuel, such as gasoline or DEF in the tank, do not start the engine.

What a Disaster Prevention Kit Does

A disaster prevention kit is a bypass and filtration kit. The best known is the S&S Diesel Motorsport Gen 2.1 kit. According to S&S, it does two jobs.

  1. Feeds the pump clean fuel. A billet bypass block mounts at the fuel control actuator on top of the CP4 and blocks the pump’s internal feed path. The pumping elements and the pump case each get their own supply of filtered fuel. On the Gen 2.1 kit, that supply splits about 25 inches upstream of the pump, so contaminated case fuel cannot back-feed into the clean side.
  2. Catches the debris. Fuel leaving the pump case goes through a dedicated return filter, a billet head with a standard Donaldson spin-on filter, before it reaches the tank, lines or supply pump.

S&S says that if a CP4 fails with the Gen 2.1 kit installed, you replace the return filter and the pump, or upgrade to a DCR. You can check that the kit did its job by inspecting the pump’s metering unit, which should be clean. S&S also published a test in which it deliberately damaged a CP4 and drove the truck about 180 miles, including towing. Diesel World reported that on teardown, the injectors, rails, return lines and tank were protected.

What a DPK does not do

  • It does not stop the CP4 from failing. The failure happens inside the pump. The kit limits the damage.
  • Not every kit performs the same. In Reddit threads, several mechanics and owners report that the S&S kit caught debris in real failures. Others report another brand’s kit did not. Some owners also warn that cheap kits come with hose that is not rated for diesel.
  • It is not compatible with a DCR. S&S states its Gen 2.1 DPK is designed only for the CP4.

What a DCR Conversion Replaces

S&S Diesel DCR pump conversion for 6.7 Powerstroke

The DCR conversion takes a different approach. Instead of containing a CP4 failure, it removes the CP4. The S&S Diesel Motorsport CP4-to-DCR conversion (part 6.7F-DCR-1) replaces the Bosch CP4.2 with a two-piston Stanadyne DCR (Diesel Common Rail) pump. S&S co-developed it with PurePower Technologies.

Per S&S:

  • It uses an eccentric drive with a pressure-lubricated cam and bushings, instead of the CP4’s roller-on-cam design.
  • It is rated for biofuel blends and low-lubricity fuel.
  • It needs no ECU calibration. It is designed to match the CP4’s output, so the stock tune works.
  • It displaces 1,250 mm³ per revolution, about 25% more than the CP4.2. That does not add power unless the tune calls for it.
  • It is CARB compliant under EO D-756-7.
  • The kit includes the pump, new high-pressure lines, a low-pressure supply and return assembly, and an adapter plate. 2011–2016 trucks also need a new vacuum pump gasket.

DPK or DCR?

There is no single right answer. Here is how owners and shops usually frame it:

  • A DPK is insurance for the rest of the fuel system. It keeps the stock pump and lowers the cost of a failure.
  • A DCR removes the CP4 failure point entirely. It is the more involved and more expensive job, and many owners consider it when the pump is being replaced anyway.

If your truck has already lost a CP4 and the fuel system is being rebuilt, that is a natural time to consider a DCR. If your pump is healthy and you plan to keep the truck, a quality DPK is the lower-cost layer of protection.

Fuel System Maintenance That Helps Any 6.7

No part replaces good fuel habits. These steps help whichever path you choose.

Change both fuel filters on schedule

A Ford dealer’s 6.7L maintenance guide says to change both fuel filters every third oil change, every 22,500 miles, or when the message center tells you, whichever comes first. Under severe use, such as extensive towing, long idle time or extended low-speed driving, the interval is every 15,000 miles or 600 engine hours. Check your owner’s manual for your model year. Use quality filters made for the 6.7L, because a restricted filter can starve the pump.

Drain the water separator

The 6.7L’s fuel conditioning module separates water from fuel. When enough water collects, the truck turns on a Water in Fuel (WIF) warning. Drain it promptly when that warning appears. If water keeps showing up, find out why. It may be a bad fuel source or a water problem in the tank.

Buy quality fuel and keep fluids separate

  • Fill up at high-volume stations.
  • Use ultra-low-sulfur diesel, which Ford requires for the 6.7L.
  • Stay within Ford’s biodiesel limits.
  • Never put DEF in the fuel tank. The caps are side by side, and DEF contamination is one of the failures on Ford’s list.

Watch the low-side pressure

Fix air leaks. Do not run the tank dry. Take a “low fuel pressure” warning seriously, because supply problems are hard on the CP4.

FAQ

Does every 6.7 Powerstroke have a CP4 pump?

S&S describes the Bosch CP4.2 as standard on 2011 and newer 6.7L Powerstroke trucks. Ford revised pump configurations between generations, so confirm by VIN before ordering parts.

Will a disaster prevention kit stop my CP4 from failing?

No. A DPK does not change what happens inside the pump. It is designed to keep debris out of the injectors, rails, lines and tank if the pump fails.

Do I need a tune with a DCR conversion?

Not for the S&S DCR. S&S says it needs no ECU calibration and runs on the stock tune.

Can I run a DPK and a DCR together?

S&S says no. Its Gen 2.1 DPK is designed for the CP4 only.

How often should I change fuel filters on a 6.7?

A Ford dealer’s 6.7L maintenance guide gives every third oil change or 22,500 miles, or 15,000 miles under severe use, or sooner if the message center tells you. Confirm the interval for your year in your owner’s manual.

Protect Your 6.7 Fuel System

Full Force Diesel carries CP4 protection and replacement parts for the 6.7L Powerstroke:

If you are not sure which option fits your truck, contact our team with your VIN and we will help you sort it out.

Sources

  • S&S Diesel Motorsport, Gen 2.1 DPK: https://ssdiesel.com/product/ford-6-7-cp4-2-bypass-kit-2011/
  • S&S, What Is a CP4 Disaster Prevention Kit: https://ssdiesel.com/what-is-a-cp4-disaster-prevention-kit-for-a-6-7l-power-stroke/
  • S&S, DCR conversion: https://ssdiesel.com/product/ford-6-7l-cp4-to-dcr-pump-conversion/
  • S&S, What Is a DCR Pump: https://ssdiesel.com/what-is-a-dcr-pump-for-a-6-7l-power-stroke/
  • S&S DCR install instructions: https://ssdiesel.com/wp-content/uploads/2025/09/8630044-Instructions-DCR-6.7F-19Sep2025.pdf
  • Ford 6.7L Diesel Fuel System Service Tips Job Aid: https://static.oemdtc.com/GSB/G0000096.pdf
  • Jim Click Ford, 6.7L maintenance tips: https://www.jimclickford.com/static/dealer-14636/6_7L_Diesel_Care_Tips.pdf