What are the symptoms of diesel high-pressure fuel pump failure?

Can you imagine if blood stops flowing in your body for a minute? The outcome is the same when your vehicle’s fuel pump goes bad. The diesel fuel pump supplies fuel from the tank to the injector. Yes, now you know why it’s also called an injector pump.

Irrespective of the type of fuel pump (either the old mechanical or new electrical fuel pump), the diesel high-pressure fuel pump failure symptoms are the same. Therefore, this article will delve into details about the common symptoms of a bad diesel fuel pump.

Symptoms of a Failing Fuel Pump?

If not solved, problems with the diesel fuel pump can lead to engine blocking. This is mostly true for cases where the fuel pump is not pumping sufficient fuel to the injector. As a driver, you should immediately attend to your fuel pump if you notice any of the following diesel high-pressure fuel pump failure symptoms.

1. Engine sputter

Engine sputters at high speed indicate a diesel fuel pump problem. These symptoms surface when you run your car at high speed on back roads or highways; the car can run many miles with brief moments of jerking before normality.

Dirty gas can also cause this symptom, but in the case of fuel pump failure, it results from failure of the injector pump to maintain the required pressure all through. So, the engine sputters, and sometimes, the best solution is a new fuel pump.

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2. Engine sputter while accelerating.

This second symptom is similar to the first; the only noticeable difference is that the sputtering occurs only when accelerating, especially after a stop. So, again, the best solution remains a new fuel pump.

3. Loss of power while under stress.

In some cases, loss of power is not noticeable under normal, low, or medium-level stress until the fuel pump is subjected to more significant stress, causing the components to fail. This does not happen in every vehicle, only those that generally tow a significant weight like pickups and trucks.

This is also noticeable when the vehicle climbs a steeper hill or in situations where it is under more significant stress. Power loss can be up to 50%, and that’s dangerous when it happens without your control. Sudden surging is also an alarming fuel pump symptom that can occur without prior notice.

Also, Read – How To Check Fuel Pressure Without Gauge?

Normal wear and tear can also lead to irregular resistance within the motor where there is a sudden switch from standard to high pressure. This allows the inconsistent supply of fuel to the engine, leading to power loss or a sudden surge.

4. The vehicle won’t start.

The last symptom is the worst, where your car will not start. If you ignore all other signs, this last one is unavoidable. When you attempt to start the car, and it cranks without bursting into life, it is an issue with your fuel pump.

Important note

These are the most common symptoms of diesel high pressure fuel pump failure. Unfortunately, though, all of them could also point to other problems in the car. However, you can troubleshoot these symptoms before visiting your mechanic.

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What can cause a diesel pump failure?

The significant causes of pump failure are engine breakdown or low gasoline. Low gasoline will put more strain on your fuel pump, and this is why you should keep an eye on your fuel levels. The first stop of troubleshooting your fuel pump failure is to check the fuel level.

Your fuel pump performance is directly proportional to your engine performance. So, a poor fuel performance indicates a gradual deterioration of your engine. Hence, the need to maintain the overall health of your car engine.

Other factors that cause diesel pump failure include – 

Wrong oil type

If your engine oil does not meet OE specifications, it fails in preventing your high-pressure fuel pump from wearing. Make sure to use the recommended oil from your car’s manufacturer.

Poor maintenance

Normal wear and tear in your car’s engine eventually affects your fuel pump and piston movement. Less pump movement means less fuel pressure; examine the camshaft lobes before installing a high-pressure fuel pump.


If your fuel pump is under stress, leakage can happen, leading to a rich fuel reading or a thick carbon buildup. Enhanced factory scan tools can reveal such leakage on your injector.

Failed Solenoid

The solenoid controls the pressure and volume of high-pressure fuel pumps. When the solenoid fails, your fuel pump returns to the low-pressure setting.

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Pressure and temperature sensors

A failed sensor can lead to a wrong diagnosis of your fuel pump. In addition, if you have a malfunctioning sensor, it can affect your fuel trims. False readings will cause the system to go into low-pressure safe mode to minimize damage to the vehicle.

What happens when a high-pressure fuel pump fails?

This is similar to the question we started with, “what happens when blood stops flowing in your body?”. When the high-pressure fuel pump fails, it stops supplying fuel into the injector in the combustion chamber. This leads to an engine failure where the vehicle does not start, not to say doesn’t move.

How do you fix a high-pressure fuel pump?

To fix a high-pressure fuel pump, perform the following procedure:

  • First, check the fuel level to ensure enough fuel is in your tank.
  • If you have a blocked fuel filter, you should consider changing it, especially if it’s an old one.
  • Next, confirm that your fuel pressure regulator is dry; a wet regulator means it’s not working correctly.
  • Finally, insufficient oil can stop your vehicle from starting; ensure the oil level is average.
  • When you turn it on, the fuel pump makes a swish sound; check your electrical circuit or test with a digital diagnostics machine if you do not hear it.

If you are a DIY car owner, steps 1 to 5 should be easy for you, if not visit your car mechanic rather than cause more harm to the vehicle.

How long does a high-pressure fuel pump last?

Your fuel pump is a critical part of your vehicle, and it deals with the continuous supply of fuel to your car’s engine. A healthy high-pressure fuel pump should last about 100,000 miles or more.

How much does it cost to replace a high-pressure fuel pump?

To perform this intermediate task of replacing your fuel pump yourself, you should budget from $75 to $250 (depending on your car’s brand and model). However, if you want a professional to do it for you, the total cost will be around $400 to $600 (including labor cost).

In addition, the total time taken to replace the bad fuel pump is between one to six hours, depending on the tools and the expertise of your mechanic. Finally, ensure proper cleaning of all sediments from the bottom of the tank to avoid recurring problems.

Wrapping Up

We have outlined the diesel high-pressure fuel pump failure symptoms and ways to fix them, either as a DIY car owner or car mechanic. Paying attention to the causes of diesel fuel pump failure and integrating it with your routine maintenance tasks will go a long way to save you from problems associated with the diesel fuel pump.

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