How to Tell If You Need to Replace Your Vehicle's Diesel Pump

Posted on: 28 August 2017

Your car or truck is made up of thousands of different parts, some of which are much more important than others. In the grand scheme of things, it doesn't matter how powerful an engine you have in the front and how full your fuel tank is at the back if the diminutive diesel pump isn't working properly. If you think that this component may be playing up, what are some of the warning signs you should be looking out for?

Electrical or Mechanical?

First of all, you should be aware of the type of pump that is fitted to your vehicle. It will be either electrical or mechanical, and this is typically dependent on the age of the car or truck. The older type is a mechanical one that's attached to the outside of the tank and relies on a diaphragm inside to operate. If you have a later-model vehicle, then it may have an electronic pump that is mounted inside the tank itself. This type of pump can generate a much more efficient pressure to feed the thirsty fuel-injected diesel engines of the modern era.

Dual Jobs

Some people think that the fuel pump only pushes diesel from one point to another, but this would be incorrect. It also needs to generate and maintain the proper amount of pressure, or your vehicle will be constantly spluttering and spitting as it goes along.

Intermittent Issues

Talking of "spluttering," if you're encountering this type of behaviour, then it is indeed likely that the pump is losing the ability to maintain that pressure. This will be particularly noticeable during highway driving, when you are adjusting your speed. Bear in mind, however, that you might have taken on a batch of contaminated fuel instead.


When you are accelerating from a traffic light, do you find that the vehicle hesitates momentarily? This could be another sign of a malfunctioning pump, as it is struggling to give you the perfect amount of fuel at a critical moment.

Poor Resistance

Sometimes, you may find that the engine will fire (or surge) when you are not pressing the accelerator. This means that too much fuel is being delivered to the engine when it is not needed. This could be because the diesel pump has lost its ability to "resist" the fuel, or in other words, regulate its supply.

Fuel Starvation

When the pump is truly on its way out, it won't have the ability to deliver any fuel to the engine at all. In this case, you'll be able to turn over the ignition and hear the engine respond, but it won't be able to crank into life as it's not getting any fuel.

Getting to Work

It is certainly a difficult job for a casual mechanic to change the fuel pump that is located within the tank itself. However, it's important to remember that this is a potentially combustible area if you do decide to DIY repairs. For this reason, it's best to get a qualified mechanic to help you replace the pump.