The diesel pump is used to supply your engine with fuel. It is therefore an important part of your vehicle, without which your injection circuit cannot function correctly. However, the diesel pump can be clogged with dirt. But what are the symptoms of a faulty fuel pump?
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⛽ What is a fuel pump?
The diesel pump is also called a booster pump or even a fuel pump . This is an electric pump located on the fuel tank (diesel or petrol) of your car. Originally, the fuel pump was only fitted to Diesel engines , but has now also spread to petrol engines (we speak of a petrol pump ).
Your diesel pump brings the fuel from the tank to the engine , which is generally located far from the petrol tank . It is therefore in the tank, immersed in diesel. Its electric motor pumps diesel, injects it into the supply circuit and circulates it to the engine. On older cars, the fuel pump motor is mechanical.
Unlike other parts of your car, the fuel pump is not really a wearing part . However, it can clog due to dirt in the gas tank. A clogged or defective diesel pump harms your engine, which is no longer supplied with fuel correctly.
⚙️ How does a fuel pump work?
A diesel pump consists of three elements:
- The electric motor , which allows the fuel to be drawn in;
- A filter ;
- A pressure regulator .
The diesel pump is part of the injection circuit fitted to any combustion engine. It sucks up diesel, which bypasses its electric motor by the action of its propeller. A conduit then transports the fuel to the injection pump located in the engine. The diesel pump allows both this transport but also the correct fuel dosage.
The injection pump then transmits the correct diesel pressure to the injectors . These are the injectors which diffuse the fuel into the combustion chamber , the last stage of the combustion circuit.
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⚠️ What are the symptoms of an HS fuel pump?
A faulty diesel pump no longer allows the proper supply of your engine. The symptoms of an out of order fuel pump are therefore as follows:
- Noise from your fuel tank : A failed fuel pump produces a hissing or whining sound when the engine is running;
- Starting problems : because your engine is poorly supplied with diesel, you will have difficulty starting your car;
- Decreases in power, jolts : the poor supply of the engine and the difficulties of combustion cause drops in power , misfires or even stalls;
- Jerks when accelerating : at high speed, an out of order diesel pump causes engine jerks;
- Failure to start completely : In the most serious cases, the symptoms of an HS booster pump even include the complete inability to start your vehicle.
What are the symptoms of an injector problem?
However, an injection problem on your vehicle does not necessarily mean that it is a fault in the diesel pump. Indeed, the problem can come from other parts, such as the injection pump or the injectors themselves. Here are the symptoms of an injector problem :
- Fuel overconsumption ;
- Fuel smell ;
- Black smoke from the exhaust;
- Lack of power when accelerating;
- Difficulty starting even though the engine is running well.
What are the symptoms of a faulty injection pump?
Symptoms of an out of order injection pump are similar to those of a failed fuel pump or injectors , hence the need to test these different parts if they occur on your car. They are manifested by:
- Power losses ;
- Engine stalls ;
- Jerks when accelerating;
- Black smoke from the exhaust;
- A smell of fuel ;
- Starting problems ;
- An ignition of the engine light on your dashboard .
An engine that does not stop when you switch off the ignition or on the contrary does not want to start is generally the symptom that the solenoid valve of the injection pump is out of order.
🔨 How do I know if the fuel pump is working?
If you are experiencing symptoms of a faulty fuel pump, you can test it. Two different tests allow you to ensure that your diesel pump is working properly :
- An electrical test : using a multimeter, you will test the booster pump and its electric motor;
- A pressure test : this allows you to test the correct injection of your diesel pump.
⚡ How to test a diesel pressure sensor?
A faulty diesel pump no longer supplies your engine with fuel correctly. However, the source of an injection problem is not necessarily the fuel pump. It is therefore important to make sure of the origin of the problem before replacing your diesel pump.
Material :
- Multimeter
- Manometer
- Toolbox
- Manufacturer's manual
Step 1: Make sure it's not an electrical problem
If you notice the symptoms of a faulty fuel pump, start by doing an electrical test . Use your manufacturer's manual to find the fuse box locate the diesel pump fuse. Inspect the fuse : if it is blown, it must be replaced.
Also check the fuel pump voltage . Use a multimeter to make sure power is flowing to the pump itself. Then also test the fuse, again using your multimeter. Your manufacturer's manual should tell you the normal voltage.
Step 2: Check the condition of the fuel pump filter
Make sure that the problem is not with your fuel pump filter . The dirt present in the fuel can indeed clog your filter over time, especially if you are used to driving with an almost empty tank. If you see debris on your filter , change it.
Step 3: Install a pressure gauge on the fuel pump
To test your fuel pump pressure, use a pressure gauge . Go to your diesel pump and lift the lid next to it to connect your pressure gauge. Use your manufacturer's manual to help you, because not all car models are the same.
Step 4: Accelerate as you test the pressure
Once your pressure gauge is plugged in, have someone turn on the vehicle's ignition . Your manufacturer's manual tells you at what rpm to do the test. Fuel pump pressure should be tested at idle. Check that the value displayed by the pressure gauge corresponds to that indicated in your manufacturer's manual. Also do an acceleration test: the pressure should increase with the rpm .
In the event of a difference in value with the normal pressure indicated in your manufacturer's manual or if the needle does not rise when accelerating, have your diesel pump changed.
🔋 How to prime your vehicle's fuel pump?
Repriming a diesel pump is particularly necessary if you have air in your circuit . Symptoms of an air leak in the diesel circuit occur especially on older diesel cars. Your engine then struggles to start and sometimes even stalls after starting. To bleed the air and prime your diesel pump, you must:
- Start by bleeding the diesel filter using the drain located at the front of the filter;
- When the diesel has finished flowing, remove the diesel filter ;
- Clean the diesel filter , or even change it in the event of a leak;
- Refit the diesel filter ;
- Bleed the air from the intake circuit by unscrewing the intake pump bleed then pumping the fuel with the manual diesel pump;
- When diesel comes out of the drain, start the engine : everything should work!
💰 What is the price of a fuel pump change?
Normally, a good quality fuel pump can last the life of your vehicle. However, if it is broken and completely stops working, it must be changed. You cannot indeed drive with an HS diesel pump. Naturally, the price of a fuel pump change depends on the model of your car.
Count between 70 and 200 € to replace your diesel pump.
The diesel pump is therefore an essential part of your car. To ensure the proper functioning of your vehicle, change your diesel pump immediately if you notice that it is faulty. Use our garage comparator to compare quotes and change your diesel pump at the best price.
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