Fuel pump


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Would you like to know what the fuel pump does in your vehicle? Then read exactly that in our blog article.

What is a fuel pump?

The fuel pump’s main task is to supply fuel to the engine’s injection system.

The pump pumps the fuel from the fuel tank via the fuel filter to the injection bar or to the high-pressure pump (for engines with direct injection systems).

In many vehicles, the fuel pump delivers more fuel than is actually needed. The excess fuel flows back into the tank via the so-called fuel return line and can then be sucked in again.

Most modern vehicles have an “in-tank pump”, which means that the fuel pump sits in the tank as a module together with the tank level sensor.

Fuel pump removed and disassembled

How does a fuel pump work?

The fuel pump in a modern vehicle is usually always electrically driven. The only exceptions here are so-called “high-pressure pumps”, which are installed in engines with a direct injection system. Nevertheless, these vehicles also have an electric fuel pump installed in the vehicle’s tank.

As soon as the vehicle is started or the vehicle ignition is switched on, the engine control unit sends a signal to the fuel pump. This signal causes the pump to switch on and start delivering fuel towards the engine. The fuel now reaches the engine or the injection valves via the fuel lines and the fuel filter.

Different types of fuel pumps

Mechanical fuel pumps

Older vehicles that have a carburetor are usually equipped with a mechanical pump. This is driven via the camshaft or via a distributor shaft. Here it is delivered fuel from the fuel tank to the carburetor. The fuel pressure here is 0.2 – 0.3 bar.

Electric fuel pumps

Nowadays, only electric fuel pumps are installed in vehicles. These are either located directly in the fuel tank or are so-called “in-line pumps”. This means that the pump is located between the tank and the engine in the fuel line.

Also, as a rule, these have a control unit. This control unit can regulate the fuel pressure as required.

Where is the fuel pump control module located?

As a rule, this control unit is installed near the tank below the rear seat bench or behind the side panel of the rear seat bench.

High-pressure pump

Ever since the so-called “common rail system (direct injection in diesel engines)” was introduced, the high-pressure pump has become indispensable. Since direct injection has also been used in vehicles with gasoline engines, a high-pressure pump is also required here.

The normal electric fuel pump delivers the fuel from the tank to the high-pressure pump.

As soon as the fuel arrives at the high-pressure pump, the fuel pressure is increased from about 6 bar by the high-pressure pump to up to 350 bar. From the high-pressure pump, the fuel flows via the distributor pipe to the individual injectors/injectors.
The high-pressure pump is driven either directly via the timing chain or via the camshaft.

High pressure fuel pump

What happens when fuel pump goes out while driving?

If the component fails while driving, the engine will normally stop shortly afterwards because there is no longer enough fuel available for combustion. It is also possible that the engine will continue to run for a short time because there is still fuel in the fuel system.

How does a fuel pump break down?

Unfortunately, like any other component on a car, the fuel pump is not exempt from wear. Wear is the most common reason for the failure of this component.
Also, deposits and dirt found in the fuel can build up in the pump, causing it to wear even faster.

Also, of course, electrical faults can cause the pump to fail, such as a defective fuse or cable.
With fuel pumps that have their own control unit, it can also happen that only the control unit is defective but the pump works without problems.

Repair fuel pump

How much is a fuel pump?

The price of a fuel pump depends on various factors, such as the model and manufacturer of the vehicle, the type of fuel pump and the installation location. As a rule, a new fuel pump for an average car costs between 200 and 800 Dollars. However, in some cases, the price may be higher or lower, depending on the specific requirements of the vehicle.

How much does it cost to replace a fuel pump?

As with the price of the fuel pump, various factors, such as the vehicle model, the type of fuel pump and the installation location is outgoing. As a rule, the replacement for the fuel pump costs an average of 500 Dollar. However, if the fuel pump is very difficult to install, the change can cost up to 1000 dollars.

Keep in mind, that every car has different software and modules built-in. Therefore specific features will vary with every model.

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