Replacing Fuel Injectors In Your Mercedes Slk230: A Step-By-Step Guide

If your Mercedes-Benz SLK230 is starting to run rough, getting poor gas mileage, or displaying an error code, it may be time to replace the fuel injectors. This process should take around two hours and requires tools such as an E12 Torx, 5mm Allen, 15mm and 17mm wrenches, and a flathead screwdriver. It is important to note that modern fuel injectors are made of plastic and are not recommended for servicing or rebuilding. Instead, they should be replaced. When replacing the fuel injectors, ensure you have the necessary parts, such as new injectors and White Lithium grease, and take the proper safety precautions, such as having a fire extinguisher and chemical-resistant gloves on hand.

Prep the car

Before starting any work on your Mercedes SLK230, there are a number of important steps to take to ensure your safety and the protection of your vehicle.

Firstly, pull out the fuse for the fuel pump and then attempt to start the car. You will notice that the car will turn over and then die. Repeat this process about 2-3 times. This will help to drain excess fuel from the system. Also, open the gas cap to help depressurize the system.

Next, ensure that the car has cooled down sufficiently. It is important to avoid working with gasoline when the car is hot. Have a fire extinguisher readily available, as there will likely be some fuel spillage, which is almost impossible to prevent. It is also recommended to wear chemical-resistant gloves to avoid getting gasoline on your hands, and have plenty of paper towels or rags on hand for cleaning up any spills.

The injector removal process should be performed in a clear, open, and well-ventilated space. It is also advisable to have an assistant nearby in case any problems arise.

Before beginning any work on the injectors, use a can of compressed air to blow away any dust and debris from the injector ports. This will prevent contaminants from entering the engine.

Open the gas cap to relieve any residual pressure in the fuel system. At the front of the fuel rail, there is a Schrader valve that can be used to further release pressure. Use a 15mm wrench on the cap and a 17mm wrench on the base of the valve to remove the Schrader valve cap.

Use a rag and a small flat-head screwdriver to release the gas from the rail into the rag. Be sure to catch any escaping gas.

Now, use two 17mm wrenches to loosen the fuel line at the rear of the rail. Be prepared for any gas that may leak out and then remove the line from the rail. This will grant you access to the E12 bolt.

Move to the front connection for the fuel line and, using a 17mm wrench, remove the line from the pressure regulator. With the line free, remove the 5mm Allen bolt holding the line to the rail. Note that there is a small nut underneath the bracket that will fall into the engine if you are not careful.

Remove the fuse for the fuel pump

To remove the fuse for the fuel pump in a Mercedes SLK230, first locate the K40 relay module. This can be found in the module box under the hood, next to the battery.

Remove the cover from the box and you will see a long relay with some fuses in the top. The K40 relay is the one with fuses in it.

Check all of the fuses in the relay to identify the fuel pump fuse. Once you have identified the correct fuse, remove it.

It is important to note that if you suspect a bad fuel pump relay, you will need to replace the complete K40 relay module, as the fuel pump relay cannot be replaced on its own.

Use compressed air to blow away dust and debris

When changing the fuel injectors on a Mercedes SLK230, it is important to prepare the car. Before beginning any work, it is recommended to pull out the fuse for the fuel pump and try to start the car. This will help drain excess fuel from the system. It is also important to open the gas cap to help depressurize the system.

Once this is done, it is time to get to work. You will be opening holes that go into the engine, so it is crucial to blow away any dust and debris from the injector ports using compressed air. This will help ensure that no dirt or debris falls into the engine during the fuel injector replacement process.

• Put on safety gear: Before you begin, make sure to put on safety goggles, gloves, and a mask. Working with compressed air and automotive systems can be dangerous, so it is important to protect your eyes, hands, and respiratory system.
• Locate the injector ports: Identify the injector ports on your Mercedes SLK230 engine. These are the openings where the fuel injectors will be removed and replaced. They are usually located near the fuel rail.
• Get your compressed air can or air compressor ready: If you are using a compressed air can, make sure it is full and the nozzle is attached. If you are using an air compressor, ensure it is connected to a power source and the hose is long enough to reach the engine.
• Blow away dust and debris: Hold the nozzle of the compressed air can or air compressor hose about 6-12 inches away from the injector ports. Pull the trigger to release the compressed air, blowing away any dust, debris, or residue that may be present. Pay close attention to the areas around the injector ports, as these are the most critical to keep clean.
• Use a sweeping motion: Move the nozzle in a slow, sweeping motion across the injector ports and the surrounding areas. This will help ensure that you remove as much dust and debris as possible.
• Inspect the area: Once you have finished blowing air, take a close look at the injector ports and the surrounding engine components. Ensure that no visible dust or debris remains. If necessary, use a clean, dry cloth to wipe down the area gently.
• Reattach the gas cap: After blowing away the dust and debris, remember to reattach the gas cap securely. This will help maintain the proper pressure in the fuel system.

By following these steps, you will effectively use compressed air to blow away dust and debris when changing fuel injectors on your Mercedes SLK230. Remember always to put your safety first when working with automotive systems and compressed air.

Remove the Schrader valve cap

To remove the Schrader valve cap, you will need a 15mm wrench for the cap and a 17mm wrench for the base of the valve.

First, locate the Schrader valve at the front of the fuel rail. Place the 15mm wrench on the cap and the 17mm wrench on the base of the valve. Now, turn the wrenches in opposite directions to unscrew the cap from the valve. Be careful not to damage the valve or the surrounding components.

Once the cap is removed, you can use a rag and a small flat-head screwdriver to release the gas from the rail. This will help to further depressurize the system, making it safer to work on. Ensure you are wearing chemical-resistant gloves and have a fire extinguisher nearby in case of any spills or leaks.

With the Schrader valve cap removed, you can now access the fuel line at the rear of the rail and continue with the next steps of replacing the fuel injectors.

Release gas from the rail

To release gas from the rail of your Mercedes SLK230, you will first need to prep the car. Pull out the fuse for the fuel pump and try to start the car. The car will turn over and then die. Repeat this step 2-3 times to help drain excess fuel from the system, and open the gas cap to help depressurize the system.

Next, make sure the car has cooled down. You don't want to be working with gasoline when the car is hot. Have a fire extinguisher handy, as there will be some fuel spillage. Wear chemical-resistant gloves and have plenty of paper towels or rags to help with the cleanup. Perform the injector removal in a clear, open, and well-ventilated space, and consider having an assistant around in case there are any problems.

Before you begin, get a can of compressed air and blow away any dust and debris from the injector ports. Open the gas cap to relieve any residual pressure.

Now, at the front of the fuel rail, you will find a Schrader valve that you can use to release any remaining pressure. Use a 15mm wrench on the cap and a 17mm wrench on the base of the valve to remove the Schrader valve cap.

Finally, use a rag and a small flat-head screwdriver to release the gas from the rail into the rag. Be very careful during this step, as gasoline is highly flammable.

Frequently asked questions