08 Duramax CP3 Pump Failure Symptoms, Solution and Life Expectancy

The first CP3 fuel pump was introduced along with the Duramax diesel engine in 2001.

It is designed for better performance and to handle more horsepower than its predecessor.

The CP3 fuel pump has a longer lifespan than the CP4 but has some minor problems.

I will discuss these minor problems today.

What Does CP3 Pump Stand for?

From the German language comes the word CP.

Actually, it doesn’t mean anything special.

However, most people think that CP3 stands for Common Rail High-Pressure Pump.

Common Rail High Pressure Pump is not official elaboration of CP3.

The CP3 injection pump has been used since Duramax was introduced in 2001.

A CP3 pump is built with a three-piston metered inlet pump.

CP3 pumps are also used in Dodge Cummins engines since 2003.

It is commonly called a high-pressure injection pump since it creates and controls high-pressure fuel.

A CP3 injection pump mainly regulates and increases required pressure and volume using electronics and FCA (Fuel Control Actuator).

How Many Miles Does a CP3 Pump Last?

How Many Miles Does a CP3 Pump Last

The CP3 is known for its high-pressure output and durability.

While CP4 has many complaints about longevity, CP3 has a reputation for a long lifespan and superior performance.

CP3 is designed to play an active role in high-mileage engines.

With proper maintenance, CP3 injection pumps last 200,000 to 250,000 miles.

08 Duramax CP3 Pump Failure Symptoms

There are 08 most common symptoms of Duramax CP3 pump failure, including low fuel pressure, no start, knocking sound, black smoke, fuel injector issue, longer crank time, etc.

Although the CP3 fuel pump handles more horsepower and lasts longer than the CP4, it has these common symptoms.

All these 08 problems are minor, So you don’t have to worry about them.

1. No Start

A failing fuel pump is the most common reason for a hard start.

It can cause a hard start if the CP3 pump does not provide enough pressure during the cranking process.

Typically, CP3 needs over 4,000 psi rail pressure to start the engine.

Lowering the pressure causes a hard start.

2. Low Fuel Pressure

Low Fuel Pressure

If the fuel pressure exceeds the requirement level, the CP3 pump fails to start the engine.

Your ECM dashboard may show a P0087 code, meaning the system pressure is less than the requirement.

The P0093 code appears when there is a problem with the CP3 pump.

3. Black Smoke

 You may notice excessive black smoke while driving.

It is also a symptom of a failing CP3 pump.

Air filters should be cleaned or replaced if they are dirty.

This will prevent CP3 from dying.

4. Knocking Sound

A knocking sound is heard when the CP3 pump fails.

So, a knocking sound is also a symptom of pump failure.

5. Blue or White Smoke at Idle in Cold Weather

The exhaust may emit blue or white smoke if the CP3 pump fails.

The smoke may not be visible if the trucks are equipped with DPF (Diesel Particular Filters).

It will help if you disconnect the exhaust to diagnose the smoking problem.

Alternatively, you can install a test pipe in the exhaust to check for the problem.

6. Fuel Injector Problem

Faulty Fuel Injectors

When your injector fails due to wear and tear, it causes your engine to hang at high RPMs.

A faulty injector also causes slow deceleration.

Such injectors need to be replaced.

7. Longer Cranking Time

A failed CP3 pump will prolong cranking time.

This is a common symptom of a bad CP3 pump.

8. Poor Engine Performance

Your vehicle performance decreases.

The fuel supply to the engine will be restricted, and the engine will not rev smoothly.

Which Pump is Better CP3 or CP4?

CP3 fuel pump is much better in terms of life span and horsepower.

As a result of the CP4 fuel pump’s inherent fault, GM has been sued.

CP4 fuel pumps have a lifespan of less than 1,00000 miles, whereas CP3 fuel pumps have a lifespan of more than 2,50000 miles.

Therefore, CP3 fuel pumps are better than CP4 fuel pumps.

How Much Does It Cost to Replace a CP3 Pump on a Duramax?

A faulty CP3 pump causes various problems in your vehicle.

To eliminate the problem, you need to replace the CP3 pump.

It will cost you around $3550, including the labor cost.

To replace the CP3 pump, follow these 09 steps:

  1. Remove the fuel supply hose
  2. Remove the alternator bracket
  3. Install the replacement pump
  4. Remove the fuel nipples
  5. Reassemble everything
  6. Check EGR hoses; if they are in working condition, tighten them; otherwise, replace them.
  7. Add a new main fuel return line
  8. Reinstall the fuel line
  9. Check the fuel pressure.

That’s all, to replace a CP3 pump.

Frequently Asked Questions

How Do I Know If My CP3 Pump is Bad?

Symptoms of a failure of the CP3 pump include hard start or no start, poor engine performance, lack of power, excessive smoke emitting from the exhaust, and low pressure.

Once you notice the signs, you should check the CP3 pump and replace it if necessary.

How Do You Test a CP3 Fuel Pump on a Duramax?

To test a CP3 fuel pump, follow these steps:

  • Clean run
  • Warm up the pump
  • Visual check (pressure waveform)
  • Test Kenn.1
  • Test ‘fill out.
  • Test zero delivery
  • Test efficiency
  • Start test (flow measurement)
  • Finally, calculate the test results.

Here is the video version of the test:

Can You Rebuild a CP3 Pump?

The rebuilding of a CP3 pump should not be attempted as a “DIY” project due to its complexity.

You can, however, fix minor issues like a leak on your own.

A complete treatment is required for rebuilding essential parts such as hard parts, special tools, or testing equipment.

Avoid attempting to repair the fuel pump on your own, as it is a complex process.

Does a CP3 Pump Need to Be Timed?

Like CP4, the CP3 pump is not timed with the engine’s camshaft and crankshaft.

So, compared to the previous injection pump models, the CP3 pump has fewer tasks to complete.

Final Words

Compared to CP4 fuel pumps, CP3 pumps are more durable and performance-oriented.

So, don’t worry about these minor problems.

Fuel pump repair isn’t a practical solution to this problem, so don’t try it.

In most cases, if your fuel pump fails, you will have to replace it, though it is an expensive job.

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