Replacing Fuel Injectors In Your 1999 Nissan Maxima: Step-By-Step Guide

Fuel injectors regulate the amount of pressurised fuel used for each engine cycle. They are usually connected to a fuel rail located on top of the engine. When a fuel injector fails or clogs, engine power is reduced and misfires occur. The check engine light will turn on and, as the issue progresses, the engine may stall immediately after starting, fail to start, hesitate under throttle or vibrate roughly. Fuel injectors tend to fail after 80,000 miles and require little maintenance.

If you own a 1999 Nissan Maxima, here is a step-by-step guide to replacing your fuel injectors. First, relieve the pressure on the fuel system by pulling the fuel pump fuse. Disconnect the negative battery terminal. Remove the accelerator cables from the throttle body. Remove the intake elbow between the air cleaner and the throttle body. Disconnect the electrical connector for the throttle position sensor. Remove the intake manifold support bolts. Remove the EGR body from the back of the intake manifold. Remove the hose that runs along the front of the intake manifold. Remove the intake manifold. Remove the fuel injector harness wires. Remove the fuel injector(s). Replace the injector(s). Reinstall all parts in reverse order. Reconnect the negative battery terminal. Start the engine and check for leaks.

How to Replace Fuel Injectors in a 1999 Nissan Maxima

Disconnect the negative battery terminal

Disconnecting the negative battery terminal is one of the first steps you should take when replacing the fuel injectors in a 1999 Nissan Maxima. This is a crucial safety precaution to prevent any sparks from igniting fuel and causing an explosion. Here are some detailed instructions on how to do this:

Tools Required:

10mm bolt

Procedure:

• Locate the negative terminal of your car battery. It is usually marked with a "-" symbol and is typically black in colour.
• Using the appropriate size wrench or socket, loosen the nut or bolt that secures the negative battery cable to the terminal.
• Carefully remove the cable from the battery terminal. You may need to wiggle it gently to detach it.
• Ensure that the cable does not touch any metal parts of the car to avoid any accidental sparks.
• If possible, cover the terminal with a piece of electrical tape or insulated cap for further protection.
• Proceed with the rest of the fuel injector replacement process, ensuring that you do not connect the negative battery terminal until the very end, just before road testing the vehicle.

Remember, working with fuel and electrical systems can be dangerous, so it is important to take your time and follow all safety precautions. If you are uncomfortable with any part of the process, it is always best to consult a certified mechanic.

Remove the accelerator cables from the throttle body

To remove the accelerator cables from the throttle body of a 1999 Nissan Maxima, follow these steps:

Firstly, locate the accelerator cables. These can be found in the engine bay, above the intake manifold by the injectors. You will need to loosen the nuts that attach the cables to the throttle body. Using a 14mm wrench, loosen the nuts on the cable line that leads to the gas pedal. This will allow you to adjust the tension on the cable.

The correct tightness of the cable is important. It should be tight enough that when you press on the gas pedal, the cable moves all the way to where it is supposed to be. However, be careful not to overtighten it, as this can cause the engine to idle. You want just enough tension so that the gas pedal responds promptly.

If you are adjusting the cable, the Factory Service Manual (FSM) provides the following instructions:

• Loosen the lockdown nut and tighten the adjusting nut until the throttle drum starts to move.
• From that position, back off the adjusting nut 1.5 to 2 turns and lock it down.

It is recommended to keep the car running while making these adjustments so that you can immediately notice if the engine starts to rev.

When removing the accelerator cables from the throttle body, be sure to also inspect the condition of the cables and the throttle body itself. Look for any signs of wear, damage, or corrosion. If any issues are found, the relevant parts may need to be repaired or replaced.

Additionally, when working with any fuel system, always disconnect the battery and take proper precautions to prevent fires.

Remove the intake elbow

To remove the intake elbow on a 1999 Nissan Maxima, you'll need to follow these steps:

Step 1: Disconnect the negative battery terminal.

Use a 10mm socket wrench to loosen the bolt and disconnect the negative battery terminal. This will ensure that there is no power flowing to the engine during the repair process.

Step 2: Remove the accelerator cables from the throttle body.

Pull the metal quarter moon sections that control the butterfly valves back towards the firewall. This will allow you to slip the throttle cables out. Then, pop the cables out of the black plastic keeper on the rear of the intake plenum.

Step 3: Unbolt the throttle cable bracket.

Use a 10mm socket wrench to unbolt the throttle cable bracket from the intake plenum. This will completely free the cables from the plenum. Push them back and out of the way.

Step 4: Label and disconnect relevant hoses and wires.

Use masking tape to label all the hoses and wires that need to be removed to access the intake elbow. This includes hoses and wires connected to the intake plenum, throttle position sensor, and other nearby components.

Step 5: Remove the intake elbow bolts.

Locate the bolts holding the intake elbow in place. Typically, there are three 12mm bolts, with the middle one holding the spark plug wire keeper. Use the appropriate socket wrench to loosen and remove these bolts.

Step 6: Carefully remove the intake elbow.

This step can be tricky. Use a pair of pliers to loosen the spring-type hose clamps connecting the intake elbow to the air cleaner piping and throttle body. Twist the hoses and use a panel tool to help pry them off. Be cautious to avoid tearing the hoses. With the clamps loosened, carefully slide the hoses off the intake elbow.

By following these steps, you will successfully remove the intake elbow on your 1999 Nissan Maxima, providing access to the throttle body and other components for further repairs or maintenance.

Disconnect the throttle sensor harness connector

Disconnecting the throttle sensor harness connector is a crucial step in replacing the fuel injectors in a 1999 Nissan Maxima. Here is a detailed guide on how to do this:

Step 1: Locate the Throttle Sensor

The throttle sensor is typically located on the right side of the throttle chamber. It is important to identify this component before proceeding.

Step 2: Disconnect the Electrical Connectors

Before disconnecting the throttle sensor harness connector, it is necessary to unplug the electrical connectors associated with the throttle position sensor. There are usually two connectors: one with a rubber boot held by a c-clip and another that can be disconnected by pressing a button and sliding the connector apart.

Step 3: Identify the Throttle Sensor Harness Connector

The throttle sensor harness connector is the wiring harness that connects to the throttle sensor. It may be held in place by a c-clip or a similar fastening mechanism.

Step 4: Carefully Disconnect the Throttle Sensor Harness Connector

Using the appropriate tools, such as a small flat-head screwdriver or needle-nose pliers, carefully release the c-clip or fastener holding the throttle sensor harness connector in place. Gently pull the connector away from the throttle sensor to disconnect it. Ensure that you do not force or pry it, as this may damage the connector or surrounding components.

Step 5: Set Aside the Connector

Once the throttle sensor harness connector is disconnected, set it aside in a safe place to ensure it does not accidentally reconnect or interfere with the rest of the fuel injector replacement process.

It is important to work carefully and methodically when disconnecting the throttle sensor harness connector. Take your time and ensure that you do not lose or damage any components or fasteners during this step.

Remove the intake manifold support bolts

To remove the intake manifold support bolts, you will need a 12mm socket, as access to this area is very limited and you will need to contort your body to reach it. There are two brackets, each with two bolts, that need to be removed.

This step is part of a larger process to replace the fuel injectors of a 3rd Generation Nissan Maxima with a VE30DE engine, although the steps may also be applied to a VG30E engine.

Frequently asked questions