Replacing the fuel pump – Here’s how it’s done!

A car cannot be operated without a running and functioning petrol or fuel pump. The service life of a fuel pump is designed to last the lifespan of the car, but, as with any other component, the fuel pump may also become damaged and defective. We will show you how to recognise damage to the fuel pump, how to replace it and what costs you should expect hereto.

How a fuel pump works

A fuel pump, which should be called a fuel pump from a technical point of view, is operated electrically in most of today’s vehicles.

The petrol pumps are primarily designed as so-called flow pumps. The fuel, in this case petrol, is transported to the injection unit via a shovel or impeller inside the pump.

The petrol pump does not operate in a regulating manner, but continuously delivers the petrol to the injection unit. Unused petrol is returned to the fuel tank via a return line. In most modern vehicles, the fuel pump itself is located directly in the fuel tank.

Is a fuel pump a wearing part?

Basically, the fuel pump should not be described as a wearing part. This is because, such a pump works reliably and without restrictions over the entire lifespan of the car.

It is therefore not intended to change or replace the pump regularly. Nevertheless, as with any other vehicle part, damage may occur.

However, these are rarely due to wear and tear, but are usually to be found in other areas. For this reason, the fuel pump is one of the car parts that are definitely not considered as wearing parts and therefore rarely sought for.

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How to recognise defects in the fuel pump

If the fuel pump fails abruptly, the engine comes to an immediate standstill. It is because a failure automatically means that no more petrol reaches the engine and thus no ignition as well. Even though such cases are rather rare, they do occur.

In these cases, there is usually a serious mechanical defect in the fuel pump, so it should be replaced immediately. However, the process may often run unnoticed.

The following symptoms can indicate a slowly developing defect in the fuel pump:

All of these symptoms can indicate an impending defect in the fuel pump. However, other factors cannot be ruled out as the cause. Still, if all these effects occur together, an incipient fuel pump defect is extremely probably.

Nonetheless, it may also be other components that are directly connected to the fuel pump that can trigger such defects. An incorrect engine control or defective cables are also possible causes.

Replace the fuel pump yourself or have it replaced?

If you are good at tinkering with vehicles, can use a lifting platform and have the necessary tools, you can change a fuel pump yourself.

• This is especially true for mechanical petrol pumps, as they are installed directly on the engine.
• Electric pumps, on the other hand, are often even built directly into the fuel tank and are therefore very difficult to reach.

If you have little experience with repairing cars and their components, you should leave the work to a specialist workshop. This is because you will have to work on both the on-board current of the vehicle and directly on the fuel and the associated gases when replacing it.

Without experience and, above all, without the appropriate safety equipment, you should not carry out the replacement of the fuel pump yourself under any circumstances.

For such an occassion, the specialist workshop is the best option, especially since such a replacement is a simple routine job there and can be done in a relatively short time.

Replacing the fuel pump step by step

1. Drive the vehicle onto a lifting platform. 2. First and foremost, check the connections, relays, fuse and engine control unit. These elements may also cause a defect and limit the reliability of the fuel pump. If you find worn cables here, for example, it is quite possible that you will not have to replace the fuel pump. 3. Now locate the fuel pump. If it is installed directly into the tank, it may well be too complicated for non-professionals to remove it. – Often the fuel pump is installed between the fuel filler cap and the rear seat. 4. Disconnect the vehicle’s battery before carrying out any work. 5. Now remove all fuel lines from the fuel pump and close them off. This will prevent any unintentional fuel leakage. – Remove the power lines and control lines from the pump. 6. Carefully dismount the fuel pump. – Make sure to secure the screws. 7. Clean the fuel pump. 8. Insert the replacement part and reassemble the individual parts step by step. – Check the tightness of the new connections before you finish the installation.

Pay attention to the following when replacing the fuel pump

• Replacing the fuel pump is very demanding for non-professionals and may also be unachievable, depending on the situation.
• You are working directly on the fuel supply. Be aware of the gases produced and protect your mouth, nose and eyes during this work.
• Avoid open flames in the workshop at all costs.
• Always have suitable extinguishing agents at hand.

Costs to be considered

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