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The CP4 pump is a high-pressure fuel pump that was installed in the 2011 Ford Powerstroke and GM Duramax diesel engines. The CP4 pump was a replacement for the CP3 pump, which was considered very reliable.
Unfortunately, the CP4 is not as reliable as the CP3 and has undergone a long series of failures, complaints, and recalls.
Also known as an injection pump, the CP4 pump takes diesel fuel and pressurizes it in the fuel rails. The pressure levels are extremely high, sometimes as much as 30,000 psi.
The pump feeds the fuel through the common rail and fuel injectors, which are designed to fire precisely on the cylinder’s compression stroke.
What Causes CP4 Pump Failure?
There are various ideas on why the CP4 pump is prone to failure, but it seems the main reason is a lack of lubrication.
One of the contributing factors is likely the ultra-low sulfur diesel that is commonly sold at gas stations these days. It’s considered cleaner for the environment, but it doesn’t lubricate as well as previous types of diesel.
As the CP4 pump uses fuel to lubricate it, this type of diesel fuel may increase friction in the metal parts of the pump. Eventually, this leads to shavings of metal rubbing off and being distributed through the fuel system.
Foreign particles in your fuel system are never a good thing and can end in catastrophic failure.
The CP4 Pump “Glitter Maker”. Source video
Another problem is air bubbles forming in the housing if the CP4 pump can’t supply adequate fuel. When there’s air in the pump, it means that metal is rubbing against metal. It may also mean that a lifter is rotating.
There’s no lock to keep lifters in place, so they can rotate 90 degrees. If it turns sideways, it can cut into the main shaft. Both of these situations eventually lead to metal particles in your fuel system.
Damage Caused By CP4 Failure
CP4 failure is typically catastrophic failure that destroys the pump. It also releases metal shavings into the fuel system. These particles eventually contaminate every part of the system, including fuel rails, injectors, high-pressure fuel lines, and the overflow valve. In this scenario, flushing the fuel system won’t adequately get rid of the residual particles.
The worst part is that the only way to be sure you have a clean fuel system again is to replace all the components. If your truck is no longer under warranty, this can cost upwards of $10,000.
What’s the Difference Between the CP4.1 and CP4.2?
There are actually two different versions of the CP4 pump. However, the only real difference between them is the amount of pumping elements. The CP4.1 has only one element and is thus used on smaller diesel engines. The CP4.2 has two elements and was used on bigger engines.
What Trucks Are Equipped With the CP4 Pump?
The CP4 pump was standard on 2011 to present versions of the Ford 6.7-liter Powerstroke.
For GM trucks, the CP4 was standard between 2011 and 2016 on the LML and LGH Duramax engines. GM switched to the Denso HP4 in 2017 when they released the L5P Duramax.
Ram didn’t put a CP4 pump in its trucks until 2019 for the 6.7-liter diesel engine. However, the automaker reversed the decision quickly and went back to the CP3 in 2021.
The following is a full list of trucks and engines that have the CP4 pump:
2011-2023 Ford 6.7-liter Powerstroke
2018-2021 Ford 3.0-liter Powerstroke
2011-2016 GM Duramax 6.6-liter LML/LGH
2019-2020 Ram 6.7-liter Cummins
2014-2023 Ram/Jeep 3.0L EcoDiesel
2016-2019 Nissan Titan XD 5.0-liter Cummins
How To Tell If Your CP4 Pump Is Failing
It’s crucial to know the signs of CP4 pump failure if you want to prevent catastrophic damage to your fuel system. Here are five symptoms to look out for.
Loss of power. If you notice a reduction in throttle response or engine power, this could be due to CP4 failure. It’s more likely to happen under heavy loads or at high speeds.
Trouble starting the engine. If you can’t get the engine to start, especially when it’s cold, this might indicate CP4 failure.
Misfires. A failing CP4 pump can cause inconsistent fuel delivery, which can lead to misfires or hesitation when stepping on the throttle.
Check engine light comes on. If your CEL comes on and you find trouble codes related to fuel pressure issues, that might indicate CP4 failure.
Increased fuel consumption. A failing CP4 pump might end up delivering too much fuel to the engine, which will lead to more fuel being burned.
A mechanics collection of CP4 pumps replaced under recall. Source
CP4 Pump Maintenance
The CP4 pump was supposed to be good for at least 100,000 miles, but it’s common for them to fail around the 10,000-mile mark. However, there are some steps you can take to prevent this early failure.
Don’t run your fuel too low. This causes parts to lose lubrication faster, which leads to more wear and tear.
Maintain correct temperature levels. Making sure that your engine, and thus your pump, remains at the right temperature can keep lubrication consistent.
Use clean diesel from quality fuel stations and use lubricating fuel additives at each fill-up to counter the current form of diesel.
Replace your fuel filters every 15,000 miles to avoid contamination.
Drain water from the system regularly to prevent buildup.
Where is the CP4 Pump Located?
On the 6.7-liter Powerstroke, the CP4 fuel pump is located near the engine where the fuel lines connect and directly across from the turbo.
On the Duramax engines, the CP4 pump is located in the front of the engine valley and behind the water pump.
On the Cummins engines with a CP4, the pump is located on the opposite side of the gear train on the other side of the front cover.
Whether you need a new CP4 pump, a CP3 pump, or and other fuel system components to repair your truck, ProSource has you covered with a quality selection of replacement diesel truck parts.
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The post What is a CP4 Pump? appeared first on Prosource Diesel.
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