Duramax Fuel Pump Location: Everything you need to know

Truck, SUV, and Van users often get baffled when locating the Duramax fuel pump. Some say it’s right in the fuel tank, while others think it’s located between the engine and the tank.

So, where’s the Duramax fuel pump location? Basically, the Duramax engines don’t follow a contemporary fuel delivery system. Instead of a lift pump, they use a Common-rail injection pump, mainly located at the front side of the engine’s valley.

A fuel pump transfers fuel to the engine. For a replacement, knowing the fuel pump location is crucial. This article discusses more. Let’s dig right in. 

Duramax Fuel Pump Location

It becomes confusing for most of the users when it comes to locating the Duramax high pressure Fuel Pump. Well, first and foremost, the Pump injection used in Duramax is commonly known as Common rail fuel injection pumps. 

In fact, the CP in CP3 or CP4 is a short form of a Common Rail High-Pressure Pump. So, when someone refers to a Fuel Pump in a Duramax engine, they generally mean to say the CP pumps. 

Unlike the petrol engines, the fuel pump, aka the injection pump in Duramax, is not located in the fuel tank or next to the engine. 

A diesel engine generally has the Injection pump located at the front side of the engine’s valley, beneath the cooler, beside the thermostat housing Y bridge. 

The injector is attached to the fuel rail, which is connected to the pump. So, the fuel pump for your diesel engine is the component you see attached to the cylinder-like rail of your fuel injection system.

The CP3 and CP4 both have been placed in the same location since the introduction of Duramax 6.6L engine variants.

However, the location of the injection pump still varies based on the engine model. But, generally, they are placed at the front side of the engine. 

Duramax Fuel Injection Pump

In 2001, General Motors first introduced the series of Duramax diesel engines. These engines are specially designed for trucks, SUVs, and Vans.

So far, the Duramax 6.6L V8 diesel engine series has introduced 6 variations: 

  • LB7 (2001-2004) 
  • LLY(2004-2006)
  • LBZ (2006-2007)
  • LMM(2007-2010)
  • LML(2011-2016)
  • L5P(2017)

As said earlier, Duramax engines don’t follow the traditional fuel pumping system. Instead of using a fuel lift pump, they feature a Common-rail injection mechanical pump that directly transfers fuel to the engine.

The task of a factory lift pump is taking fuel from the fuel tank and transferring it to the fuel injector. Injectors are devices that push fuel to the internal-combustion engine.

On the other hand, the fuel injection pump draws fuel from the fuel tank, creates a vacuum, and transfers the fuel to the engine through the fuel line. 

The primary function of the fuel injection pump is to boost the pressure of the fuel so that the fuel can be sent to the fuel injector in the correct amount.

The fuel injection pump delivers fuel to the engine based on the engine’s speed and load.

The fuel pressure that is created by the injection pump is significantly higher than the lift fuel pumps. Although, the pressure varies depending on the type of engine.

Related: LB7 Injector Replacement Cost – Breakdown Guide for 2022

Duramax Injection Fuel Pump Types

Over the last decade, the high-pressure Fuel injection pump has revolutionized the diesel fuel system with modern advanced technology.

So far, the CP3 injection pump and the Cp4 pump are most popularly used in Duramax.

Both the CP3 and CP4 pumps have been chosen by millions. They have a modular construction, which can be adapted based on the customer’s needs.

For the extreme pressure handling capability, these two pumps have become primary choices for most diesel fuel systems.

Cp3 Fuel Injection Pump

Since the introduction of the Duramax diesel engine, the Bosch CP3 pump has been a popular choice for the diesel fuel system. Bosch CP3 pump first came out with the Duramax engine LB7 variant in the year 2001.

The CP3 injection pump has a Pinned Piston which makes them a 3 piston high-pressure fuel pump. Even in the era of the updated CP4 injection pumps, many users prefer to replace the CP4 pump with the CP3 pump.

Cp4 Fuel Injection Pump

The Bosch CP4 Pumps, on the other hand, were released in 2011, and it came out with the Duramax engine LML variant.

The basic difference between the CP3 and CP4 Injection pumps is that the CP4 has a higher fuel volume, and this pump comes with 2 pistons.

Both the common rail injection pump comes with a dual setup, makes the Injection pumps unbeatable, and is praised for their ability to supply a higher rail pressure.

The evolving technology of CP3 and CP4 have constantly been boosting the fuel system and helping the engine to work optimally.

A failure of the fuel injection pump means the shutdown of the total vehicle system. For that reason, the common rail injection pump is often called the heart of the entire fuel system. 

Duramax Fuel Pump Maintenance

As previously stated, the injection fuel pump’s job is to maintain the hour flow rating by generating the proper pressure and providing the right quantity of fuel.

An interruption in the fuel flow system would be detrimental to the engine. As a result, it is necessary to accurately maintain the Pump’s health, specifically for the engine to perform well under a variety of conditions.

Because the injection pump is located deep inside the structure, this component is frequently overlooked. Regular maintenance would make the Pump last for years and provide the engine with the power it requires.

Here are some tips for keeping the Injection Pump in good working order.

  • The fuel pump should never be empty
  • Inject clean and high-quality fuel into the fuel tank. 
  • Change the fuel filter on a regular basis. 
  • Try to Keep the Pump Cool.

Nevertheless, there is no alternative to visiting the mechanics regularly. This would inform you of the detailed condition of the vehicle and let you know when it needs a change.

People Also Inquire About

Does Duramax Have a Fuel Pump In-Tank?

Duramax turbo-diesel engines don’t have a conventional fuel pump. Instead, it has a Common rail injection pump located at the front of the engine valley.

You’ll commonly find the fuel pump in the tank or between the engine and the tank in a petrol engine. 

Where Is the Fuel Pump on A 2014 Duramax?

Since 2011, most of the Common rail injection pumps that have been attached with the engine are CP4. However, both the CP3 and CP4 Injection pumps are attached with the fuel rail and injector. You’ll find them at the top of the engine head.

How Long Does Cp4 Pump Last?

The longevity of the CP4 Pump depends on how many miles you have driven it. Generally, the CP4 Fuel pump lasts on an average of 2,00,000 miles. However, the main culprit behind the failure of a fuel pump is the air inside the pump.

What Does Cp3 Pump Stand For?

CP injection pump stands for Common rail high-pressure pump, and the 3 indicates the version of the pump.

Who Makes Cp3 Pump? 

CP3 injection pump is produced by Bosch, which is a leading global supplier of automotive technology and services. 


The Duramax fuel pump location is often confused as it’s placed deep inside the components of the vehicle. It’s understandable that if you’re not an expert mechanic, it will be difficult to spot the injection pump.

Therefore, this article has made an effort to clarify the location of the common rail injection pump and its function and manufacture for your convenience.

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