Injection Pumps and Regulators

(24) Results Found

Injection Pumps and Regulators

In Duramax trucks, the fuel injection pump is a common failure point, especially for CP4 equipped trucks. The CP4 replaced the CP3 as the injector pump on newer Duramax trucks, but quickly proved to be a less-than-stellar upgrade. Many CP4 Duramax owners are converting back to the reliable CP3 before and after catastrophic failure. Merchant Automotive is going to carry direct replacement Duramax injection pumps as well as CP4 to CP3 conversion kits to get your fuel system working great again.

The fuel injection pump is a component that is mounted on your Duramax engine that is responsible for pumping fuel to your injectors. This pump keeps your fuel delivered in a certain timed rhythm to keep your diesel engine running smoothly. For comparison, it does the work of the throttle and ignition system that is used in gasoline engines. The early Duramax trucks used a CP3 style fuel injection pump that was pretty reliable and never really had any issues other than failure from old age. Over time, the CP3 was phased out for the CP4 unit as it was a lower cost and lighter compared to the CP3. As years progressed, Duramax owners noticed that there were far more problems with the CP4 when compared to the CP3. CP4 failure was causing catastrophic failure to Duramax fuel systems, resulting in repairs up to $10,000. This caused manufacturers such as Merchant Automotive to develop CP4 to CP3 conversion kits to remove your CP4 pump and install a brand new CP3 pump for better performance and reliability.


How Do I Know If My Fuel Injector Pump Is Bad?

The injector pump on your Duramax engine is just one of the many components of your fuel system that can go bad. If your fuel injector pump starts to malfunction or fail, it is going to be very noticeable as it supplies fuel to your injectors. If you are experiencing any of the symptoms below, your fuel injector pump should be an area of concern and checked out by a professional.

  • Engine Running Rough
  • No Start Condition
  • Hard Start Condition
  • Misfiring
  • Performance and Power Lower Than Usual
  • Excessive Smoke Coming From The Exhaust

What Year Duramax Had CP4 Problems?

The CP4 fuel injection pump in 2011-2016 Duramax trucks suffer high pressure fuel pump issues due to lack of lubrication. The CP4 was designed to be a more efficient pump than its predecessor, the CP3 pump. However, the CP4 proved to be less reliable than the CP3. An LML CP4 pump failure will present itself with a hard start or no start condition and can result in the following trouble codes: P0087, P0088, P0191, or P128E. This can be confirmed by removing the CP4 pump and fuel pressure regulator and checking for cracks and metal debris on the fuel pressure regulator screen. This comprehensive kit will replace all of the needed components when dealing with a CP4 pump catastrophic failure.

Where Is The Injector Pump On A 6.6 Duramax?

Whether you are diagnosing a bad injector pump or are converting from a CP4 to a CP3, you are going to need to know where the injector pump is on your 6.6 Duramax. At first glance of your Duramax, you are going to have a hard time finding it. The fuel injector pump is going to be tucked up in the front of the Duramax engine valley behind the water pump.