The 2011-2016 Duramax suffers from a high pressure fuel pump issue unique to this year range. Failure of this CP4 pump is usually catastrophic, causing instant contamination of the entire fuel system with metal particulates. Chances are, if you’re looking at this page, you’re well aware of the problem. Below we will discuss the reasons for this failure, how to diagnose a pump failure, and show you the parts you need to properly fix your vehicle.

Why does it fail?

The short answer: lack of lubricity. Lubricity is most commonly defined as the ability of a fluid to minimize the degree of friction between surfaces in relative motion under load conditions. The CP4 injection pump creates higher pressures with less volume than its predecessor, the CP3 pump. Although this makes it a more efficient pump, the lack of volume creates a lack of lubrication since these pumps rely on the diesel fuel to act as a lubricant. In addition to the higher pressure and lower volume, the removal of sulfur from modern diesel fuel (Diesel #2 or Ultra-Low Sulfur Diesel) also destroys compounds that exist in the fuel naturally that would normally contribute to increased lubricity. Some fuel resellers mix lubricity-increasing additives into their fuel prior to sale, but this is not consistent and not well-regulated. Using a commercially available diesel fuel additive can be helpful, but cannot be guaranteed to prevent CP4 pump failure.

What can you do to prevent this?

The easy and least expensive fix is to install a FASS Diesel Fuel System or there are conversion kits to replace your CP4 pump with the CP3 pump. You can use High quality fuel additives such as Liquid Moly Diesel Purge or Super Diesel additive but that can't guarantee it won't fail. Come on over to EDP or call and speak with Robert and he can explain the benefits and costs to upgrade the pump or install a FASS system.