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How to replace fuel injectors?

How to replace fuel injectors?

Injectors ensure optimum combustion for your engine. They are responsible for spraying fuel into the engine's combustion chambers. The fuel is delivered to the injectors by the injection pump. As soon as one of them fails, combustion can fail, fuel consumption rises and the engine loses power. So it's vital to replace the faulty injector as soon as possible.

Injectors: function and structure

One thing is certain: a combustion engine cannot function without injectors. Depending on the engine, these important automotive parts are also known as injection valves.

Their mission is to inject a precise quantity of fuel into the combustion chamber. The injector sprays the fuel, which is then ignited by the spark plug. This process is timed to the millisecond. Over the lifetime of a commercial vehicle (e.g. a truck), an injector performs between one and two billion injections. An injector consists of several parts:

  • High-pressure fuel inlet connection
  • Fuel return line
  • Injector body
  • Injector needle
  • Compression spring

All these parts are perfectly matched to each other and cannot be replaced. In a car, fuel is compressed and sprayed by the injector through up to five holes.

fuel injector

When and why to replace an injector?

Injectors are also essential to the smooth running of a car, especially the engine. The average life of an injector is 150,000 km. However, failure can occur at any time. It's a good idea to replace injectors when they fail, as this can lead to more serious failures in other engine components.

How do I change an injector?

Step 1: Identify and Locate the Injector

The next step is to locate the bad fuel injector once you've identified it. In most vehicles, fuel injectors are located in the engine compartment near the intake manifold. They may be hidden by other components, so you may need to remove some parts to gain access. Again, for specific instructions on how to locate the fuel injectors in your vehicle, refer to your owner's manual or a repair manual.

Step 2: Prepare Your Vehicle for Injector Replacement

First, make sure you have enough room to work. Next, gather all of your tools and materials and keep them within easy reach. Next, you'll need to release the pressure in the fuel system. This is important to prevent fuel from spraying when you remove the injector. Consult your owner's manual or a repair manual for specific instructions on how to relieve pressure in your vehicle's fuel system. You may need to use a fuel pressure gauge to check the pressure and release it if necessary. Once the pressure in the fuel system is released, you're ready to begin the injector replacement process.

Step 3: Disconnect the Battery

If you've just driven your vehicle, allow it to cool down before opening the hood. Then put on your safety gloves and disconnect the battery. Start by disconnecting the positive terminal, then the negative terminal.

Step 4: Remove the Injector Connector

To remove the injector connector without damaging it, you'll need to remove the clip that holds the metal clamp on the cable.

Step 5: Remove mounting hardware

The injector is usually held in place by bolts or screws. Remove and set aside the mounting hardware using the appropriate socket or wrench.

Step 6: Carefully Remove the Old Injector

Once the fuel line and mounting hardware have been removed, the old fuel injector must be loosened. Carefully remove it from its mounting location, being careful not to damage surrounding components. If the injector is stuck, you may need to gently rock it back and forth to loosen it.


Step 7: Clean the Installation Area

Before installing the new fuel injector, it's important to clean the installation area. Use a clean cloth to wipe away any dirt or debris that may have accumulated. This will help ensure a good seal and prevent debris from entering the fuel system.

Step 8: Install the New Injector

Before installing the new fuel injector, dip the tip or nozzle end in a small amount of engine oil. This will wet the seals and make the rest of the process easier. The new injector should be carefully inserted into the cylinder by hand. Once it's in place, be careful to guide it correctly so that its tip doesn't hit any obstructions that could cause serious damage. With diameters typically 200 microns or less, injector nozzle tips are extremely small and the slightest impact can damage them.

The injector must fit tightly into the cylinder with minimal force. Never use a hammer or other instrument to force an injector into place. Once this is done, a clamp should be used to lock the injector into the cylinder. Use the torque wrench to tighten the clamp bolt to ensure proper torque and angle.

Step 9: Reassemble all components

Once you've installed the new injector, you'll need to reconnect its fasteners. Start with the hose and injector flange. Then reconnect the injector connector and install the metal clamp.

Step 10: Check for Leaks

The first step in testing your new injector is to check for leaks. Start the engine. Run the engine for a few minutes. Then carefully inspect the injector and surrounding area for leaks. If you find a leak, turn off the engine and tighten the fuel line or mounting hardware as necessary. Then retest the injector.

Step 11: Check Fuel Pressure

Next, check the fuel pressure to make sure it's within the proper range. Consult your owner's manual or a repair manual for the correct fuel pressure range for your vehicle. Check the pressure with a fuel gauge and compare to the recommended range. If the fuel pressure is too high or too low, there may be a problem with the new fuel injector or the fuel system as a whole.

Step 12: Test the vehicle

Taking the vehicle for a test drive is the final step in testing the new fuel injector. Pay close attention to the engine operation and listen for any unusual noises or problems. If the engine runs smoothly and there are no problems, the new fuel injector has been successfully installed.

Tips: If you have your injectors changed at a trusted independent shop, you can really save money. After consulting with the garage, you can order your injectors from MOSTPLUS. We offer injectors and all related spare parts at competitive prices.

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