Fuel Injector Replacement: Nissan Kad24de Engine Guide

Replacing the fuel injectors on a KA24DE engine can be a straightforward task. The process involves relieving fuel pressure by unscrewing the gas cap, unfastening the electrical bar and the injector screws, disconnecting the electrical connection, and using a flat-head screwdriver to remove the old injector. It is important to cover the screwdriver with a cloth to minimise damage. After coating the new injector rings with Vaseline, the new injector can be placed into the hole and pushed in. If only replacing the o-rings, the injector tailpiece should be cleaned before reinstallation.

Relieve fuel pressure

To relieve fuel pressure in your vehicle, follow these steps:

Firstly, it is important to loosen or remove the fuel filler cap to relieve pressure build-up in the tank. Always disconnect the negative battery cable when working on the fuel system of a car to prevent sparks, which could ignite fuel and fuel vapours.

There are several methods to relieve fuel pressure, depending on your vehicle's make and model. Here are some of the most common systems:

Relieving Pressure with the Fuel Pressure Regulator:

• Locate the fuel pressure regulator on the fuel rail, which is mounted along the top area of the engine. Ensure that it is vacuum operated.
• Disconnect the vacuum hose from the top of the fuel pressure regulator by hand.
• Connect a hand-operated vacuum pump to the top of the pressure regulator.
• Apply approximately 16 inches Hg of vacuum to push the fuel in the lines back into the fuel tank.

Relieving Pressure with the Fuel Pump Connector:

• Access the sending unit/fuel pump assembly, which may be located on top of the fuel tank, or underneath the rear seat, in the trunk, or under the trim.
• If there is an access door above the tank, remove the rear seat or the trim to access the fuel tank. Unscrew the mounting screws on the fuel tank access door.
• If the fuel pump is accessed from underneath, secure the vehicle on jack stands before locating the fuel pump assembly.
• Unplug the fuel pump electrical connector on the sending unit/pump assembly.
• Start the engine and let it idle until it stalls, then turn off the ignition switch and disconnect the negative battery cable.

Relieving Pressure with the Fuel Pump Fuse and Relay:

• Locate the fuel pump fuse, usually found under the dashboard or in the engine compartment, often on the driver's side. It may be marked for easy identification, and you can also refer to your owner's manual.
• Remove the fuse or the fuel pump relay by hand or with a pair of pliers.
• Start the engine and let it idle until it stalls, then disconnect the negative battery cable.

Relieving Pressure with the Test-Port Valve:

• Locate the Schrader valve on the fuel rail around the top of the engine. This valve is used for test purposes and resembles the air valve on a bicycle tire.
• Unscrew the valve cap if there is one and wrap shop rags around the port valve to catch the fuel that will squirt out.
• Depress the valve using a small screwdriver until fuel stops flowing through the valve, then replace the test-port valve cap.

Unfasten screws

To replace the KAD24DE fuel injectors, you will need to unfasten two philip head screws for each injector. If the screws are corroded, you may need to use WD40 and an impact screwdriver to unfasten them.

• If you suspect that the screws may be corroded, apply WD40 to the screws before attempting to remove them. This will help to loosen them and make them easier to turn.
• Using an impact screwdriver, begin to carefully unfasten the two philip head screws that hold each injector in place. Be gentle and take your time with this step, as you do not want to strip the screws or damage the surrounding area.
• If the screws are extremely tight or difficult to turn, you may need to apply more WD40 and wait a few minutes for it to take effect. You can also try using a higher-torque impact screwdriver if you have access to one.
• Once the first screw is completely removed, set it aside in a safe place so that you do not lose it. Then, move on to the second screw and repeat the process.
• If you encounter significant resistance or if the screws seem to be stuck, do not force them. You may need to take your car to a mechanic or seek further advice to avoid causing damage.
• Once both screws for an injector are removed, carefully set them aside and move on to the next injector. Repeat the process until all the injectors have been removed.

Remember to work carefully and patiently when unfastening the screws, as this will help to ensure that you do not cause any damage to the fuel injectors or the surrounding components.

Disconnect electrical connection

Disconnecting the electrical connection from your fuel injectors is a delicate task that requires careful attention to avoid damage. Here is a step-by-step guide on how to do it:

Step 1: Prepare Your Tools and Work Area

Before you begin, gather the necessary tools, such as a flat-head screwdriver, and ensure your work area is well-ventilated. It is important to take safety precautions as there is a risk of fuel leakage.

Step 2: Locate the Fuel Injectors

Identify the fuel injectors and the electrical connectors attached to them. You may need to refer to a repair manual or a video tutorial specific to your vehicle's make and model to locate these components accurately.

Step 3: Disconnect the Electrical Connectors

Using a small flat-head screwdriver, carefully pry or push the metal clip or locking mechanism on the electrical connector to release it. Some connectors may have a release button that you can press to disconnect. Be gentle to avoid breaking the plastic. If there is limited space to work with, consider removing the fuel rail first to gain better access to the injectors.

Step 4: Separate the Connector

Once the clip is released, carefully separate the electrical connector from the fuel injector by pulling it straight up and away from the injector. Be cautious not to damage the connector or the injector itself.

Step 5: Store the Fuel Injectors (if applicable)

If you are replacing the fuel injectors, it is a good idea to keep the old ones organised and stored neatly. You can use a piece of cardboard with holes punched in it to hold the injectors, ensuring you return each injector to its corresponding spot.

Step 6: Clean the Area

Before proceeding with any further repairs or installations, it is important to clean the area. Fuel may have leaked during the disconnection process, so use a suitable absorbent material to wipe down the injectors and surrounding components.

Remember to refer to a qualified mechanic or a detailed repair manual for your specific vehicle if you are unsure about any steps or procedures. Working on fuel injectors requires caution and a good understanding of your vehicle's fuel system.

Remove old injector

To remove the old fuel injectors from your KA24DE engine, follow these steps:

Firstly, relieve the fuel pressure by unscrewing your gas cap. You may also want to unfasten the 10mm bolts holding the electrical bar. Next, unfasten the two Philips-head screws for each injector. If the screws are corroded, you may need to use WD40 and an impact screwdriver to remove them. Once the screws are removed, push in on the fastener and pull off the electrical connection at each injector.

Now, you can begin removing the injectors. Take a large, flat-head screwdriver and twist it to pop off the fuel injector. It is recommended to cover the tip of the screwdriver with a cloth to minimise damage. Do not use a vice grip, as this can damage the injectors. Alternatively, you can use a small flat-head screwdriver to pry against the slots on the injector body, or where the angle of the injector meets the rail. This method is less likely to damage the injectors.

If your injectors are seized in place, you may need to use some WD40 and a flat-head screwdriver to gently wiggle and pry them out. You can also try using vise grips, but be very careful as this method can easily damage the injectors. Pull straight up while slightly twisting the vise grips. If this doesn't work, you can try using a big flat-head screwdriver to tap the back of the injector and dislodge it.

Install new injector

To install new fuel injectors, you will need to first lubricate the new fuel injector O-rings with clean engine oil. Then, place the new injector into the hole, and use a large screwdriver to push it into place. Alternatively, you can use a socket and your palm.

If you are replacing the injector O-rings, be sure to clean the injector tailpiece before putting the injector back. You should also coat the new injector rings with Vaseline.

After installing the new injectors, reattach the fuel rail and reconnect any electrical items or parts that you removed. Ensure each part is fully seated and secured.

Once you have finished the installation, run the engine and inspect for leaks from the fuel system. If the car does not start right away, allow it to crank for a few seconds to pressurize the system, and check that any fuses and relays are installed and working.

Frequently asked questions