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How to Clean Diesel Injectors: An Ultimate Guide!

How to clean diesel injectors

The fuel injector is a small electrical part that is responsible for delivering fuel by injecting the diesel fuel directly into the cylinder. This diesel injector is made to withstand extreme temperature and pressure in the cylinder while delivering fuel in fine mists. However, deposits can build up in the diesel injector’s tips over time. You should know how to clean diesel injectors since they need to be clean so they can function properly and help make sure that your diesel engine is always running at its optimum performance. The most common ways on how to clean diesel injectors include adding fuel additives regularly, adding a fuel injector cleaner to your fuel system, and if your injectors are really clogged, you can use an injector cleaning kit. You can also take your car to a trusted mechanic to have your injectors disassembled and reassembled for a heavy cleaning.

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How to Clean Diesel Injectors: Can Diesel Fuel Injectors Be Cleaned?

As mentioned above, fuel injectors are small electrical parts responsible for delivering fuel by injecting it directly into the cylinder of your diesel engine. It might seem that its task is pretty simple but the fuel injector is known as one of the most complex components of a car engine. In fact, it has undergone much experimentation over the years.

The fuel injector is built and designed to withstand extreme temperatures and pressure which are produced inside the cylinder while delivering diesel fuel in a fine mist. The said fuel should also be circulated in the cylinder to make sure that it is spread out and distributed evenly.

Diesel injectors do not work like the injectors found in gasoline engines. Fuel and air are being mixed together for a while before they are transmitted into the cylinder in gasoline engines. On the other hand, diesel engines’ fuel is injected directly into the cylinder before it gets combined with the air. This will then give the engine appropriate power to turn your car’s wheels and move forward.

The fuel injector is a very important part of the engine. Without it, your car will not move. Fuel injectors need to be clean in order to function properly. When it is clean, your diesel engine will run at its optimum performance. It will also help improve the car’s fuel economy. Clean fuel injectors mean that they will inject the diesel fuel in an optimum atomized mist which is cleanly burned and your car will get the full benefit out of the diesel fuel.

This is why you need to know how to clean diesel injectors. Fuel injectors become dirty and suffer deposit build ups over time. This can happen since there will always be dust in the air, debris, or other small particles in diesel that could be accumulated in the diesel injectors. Deposit build ups can also occur in the tips of the fuel injectors. This usually happens when there is diesel fuel left in the tips of the fuel injector after the engine is turned off. It will be cooked and will turn into deposits and this can affect the clean, perfect spray of the diesel injector.

So you ask, can diesel fuel injectors be cleaned? Yes, if you know how to clean diesel injectors. You will have to clean the diesel injectors since the gunkier or dirtier they get, the harder your diesel engine struggles. If the problem is ignored and your diesel injectors remain dirty, it will cause a significant decrease of your car’s fuel mileage. If your engine continues to work harder because of it, it can lead to engine problems such as poor performance, power loss, and other acceleration issues.

How to Clean Diesel Injectors: What is the Best Way to Clean Injectors?

Knowing how to clean diesel injectors will be very beneficial when your car’s injectors are dirty and have deposit build ups. Cleaning dirty diesel injectors is very vital in restoring the performance of your engine and in improving its fuel economy. What is the best way to clean injectors?

Here are some of the most common ways how to clean diesel injectors:

Adding Fuel Additives

 Adding fuel additives is one of the methods on how to clean diesel injectors. To do this method, you just have to follow these simple steps:


  • You need to buy a fuel additive that is compatible with your car since not all fuel additives work with diesel engines. You can check the packaging of the fuel additive to be sure.
  • Turn off your engine and remove the key from the ignition to be sure. Your diesel engine should not be actively burning fuel.
  • It will work better if your fuel tank is almost empty so the fuel additive can flow through the fuel system with high enough concentration to clean it thoroughly.
  • Open the fuel tank of your car and add or pour the recommended amount of fuel additive into your tank. The amount of fuel additive that you need to add in your tank is based on the size of your car’s fuel tank. The bigger your fuel tank is, the more fuel additive you need to pour. To make sure you are adding the right amount, you can check its packaging or its instructions. You need to measure the right amount, use a funnel if you have one, and add it into your tank.
  • Once done, you need to fill up your fuel tank with diesel. Then insert your key in the ignition and turn on the engine so the fuel additive can start circulating through the fuel system and do its job. You can either drive around your car for a while or let it idle for about ten minutes. The fuel additive can help maintain your diesel injectors and prevent them from any deposit build ups.

The methods on how to clean diesel injectors using fuel additives can vary depending on the brand of the fuel additive your purchase. Make sure that you will read the packaging for the instructions.

Adding Fuel Injector Cleaner Straight to the Fuel Filter

Another method you can do that is considered one of the best methods on how to clean diesel injectors is adding fuel injector cleaner straight to the car’s fuel filter.


  • Assuming that you already bought a fuel additive that is compatible with your diesel engine, insert your key in the ignition and start your car. Let your car warm up for about 3 to 4 minutes and then turn it off and remove the key from your ignition.
  • Then you need to remove the primary fuel filter and drain the fuel filter or filter housing. It will be better if you replace your old filter and install a new one. Although it is not required, the experts are recommending it.
  • You need to pour the fuel additive and fill the entire filter and housing cavity.
  • Install a new fuel filter if you choose to replace your old one. This will make sure that there will be no air in the fuel filter or housing.
  • Once done, you can then insert the key in the ignition and start your engine. Allow your engine to run for about two minutes and turn it off again.
  • Remove the key from your ignition and with the engine turned off, allow the fuel additive to work by leaving it off for the next 5 to 15 minutes. By doing so, the fuel additive will be soaked into the dirt or gunk in the fuel system.
  • After that, you will have to restart your engine and allow your engine to run, driving your car for around 30 minutes. This gives the fuel additive time to get the cleaning done. To help achieve the optimum cleaning process, you can try to run your engine hard while driving since it will build up and heat compression.


Using a Fuel Injection Cleaning Kit

 This is also one of the methods used on how to clean diesel injectors. This method is ideal when your diesel injectors are clogged and are in need of a heavy cleaning. You just need to make sure that you buy a fuel injection cleaning kit designed for diesel injectors. Make sure that you read the instructions since it can vary from brand to brand. The instructions listed below are the steps commonly used by most fuel injection cleaning kits.

  • Purchase a fuel injection cleaning kit that is compatible with your engine. Make sure to read the packaging or the cleaning kit’s details to know you are getting the right one. Some fuel injection cleaning kits may require you to buy additional connectors or adapters. Check for any specific instructions or tools required in using the cleaning kit.
  • Since you will be dealing with your engine’s fuel system on what you are trying to do, you need to make sure you are safe. You need to make sure that your engine is off. Remove the key from the ignition to be sure.
  • Once done, you need to remove the cap from the gas tank to make sure there will be no extra pressure building up in the tank.
  • Locate your fuse box under the hood or in the engine bay. Once found, open the fuse box and find the fuel pump fuse. If you are not sure where it is located, you can consult your owner’s manual or the diagram on your fuse box. You can then remove the fuse. You can pull it out of the fuse box by using a pair of needle nose pliers.
  • You need to make sure that the fuel pump is disconnected so the fuel injection cleaning kit can do its magic on the fuel system. You can confirm if it is already disconnected by starting your engine. You will know if it is disconnected when it seems that your engine is trying to start and you hear the click but it can’t.
  • Your car’s fuel rail is connected to the diesel connector and it is the one that supplies diesel to the fuel pump. The pump has already been disconnected so you can now disconnect the output hose and then connect it to the cleaning kit. You will see an indication where you can attach the hose. You need to make sure you follow the proper amount of air pressure that flows into the kit. You can adjust the air flow by turning the dial.
  • Once done, you can start your engine and allow it to run for about 15 minutes so the cleaning kit can run its cleaning solvent throughout the fuel system. Do not drive your car around but just let it idle while the solvent is cleaning the diesel injectors. You need to allow the engine to run until the engine stops. This means that the cleaning solvent has run out.
  • When the engine dies and stops running, you need to turn off the car. Remove the key from the ignition, replace the fuel pump fuse, and disconnect the hose from the cleaning kit. After that, you can then connect the output hose to the fuel rail again.
  • Once everything has been put back in place or reconnected, you can now start your engine. You should be able to hear it run smoothly after the cleaning. There should be no unusual noises. You can drive your car around to make sure that everything is working properly. If it seems that there is a problem, you better have it checked by a mechanic immediately.


Knowing how to clean diesel injectors can work wonders. It is important that your diesel injectors are always clean since it can affect your engine’s performance. Cleaning your injectors can restore your engine’s performance as well as improve your fuel economy. However, you need to make sure that your diesel injectors are running dirty and not worn. If it is already worn, no amount of cleaning can help restore it to the way it was. If it is worn you will have to have your diesel fuel injectors replaced instead.

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