Replacing Fuel Injectors In A Commodore: Step-By-Step Guide

If you're experiencing issues with your Holden Commodore VZ, it may be time to consider replacing the fuel injectors. Fuel injectors play a crucial role in controlling and atomising the fuel that enters your car's engine. Over time, contaminants can cause build-up or rust, leading to potential issues such as leakage or the injector nozzle becoming stuck. While cleaning the injectors may be a temporary solution, sometimes the best course of action is to replace them entirely. This process involves purchasing a set of new fuel injectors suitable for your Commodore VZ and carefully installing them, ensuring that the injector O-rings are properly sealed. By taking on this maintenance task, you can ensure your car runs smoothly and efficiently.

Cleaning blocked injectors

If your fuel injectors are blocked and won't fire any fuel through them, injector cleaner won't be of much help. However, there are ways to clean them.

One way to clean blocked fuel injectors is to use isopropyl alcohol to clean fuel varnish from the external tip of the injector and its ports. You can use a 9V battery to activate the injector and pour a small amount of isopropyl alcohol into it so the fluid gets inside. Disconnect the battery after a minute and use a can of carbi cleaner to blow the dissolved residue out of the injector. Wrap some electrical tape around the plastic squirt nozzle to ensure a tight fit into the injector input port. Then, connect the 9V battery again to activate the injector and press the carbi cleaner button.

Another way to clean fuel injectors is to use a machine that fires a special chemical at different pulses to dissolve varnish and other residue. This method also involves replacing the fine strainers, seals, and o-rings.

A third option is to use an ultrasonic cleaning method, which involves removing the injectors from the vehicle, pre-flow testing and checking them, placing them on an ultrasonic cleaning bench with the fine-mesh filters removed for 12 minutes, and then placing them on the flow-tester again and re-checking.

Finally, you can try running a tank or two of premium fuel, which has more additives and should clean the system a little. However, this method may not be very effective if the injectors are very dirty.

Flushing the tank and lines

Step 1: Prepare the Vehicle

Before starting, park your VZ Commodore on a level surface and engage the parking brake. Ensure the engine is cool and secure the vehicle on jack stands if necessary. Locate the fuel tank and lines, which can be found near the firewall. Identify the fuel lines correctly: the bottom pipe on the firewall is the vapor purge valve, while the feed and return lines can be identified by briefly turning the key to the reds and observing fuel flow.

Step 2: Disconnect the Fuel Lines

To disconnect the fuel lines, start by removing the clip that holds them in place. Then, use a disconnect tool to separate the lines. You can purchase a set of plastic or metal disconnect tools at a reasonable price. Place the tool around the steel line and insert it into the larger part of the fitting to press the tangs and release the line.

Step 3: Flush the Fuel Lines

Obtain a suitable solvent or cleaning solution specifically designed for flushing fuel lines. Follow the instructions on the product and take the necessary safety precautions. You may need to flush each line individually, ensuring that the solution flows through the lines to remove any built-up contaminants. Use a container to catch the flushed fluid, and properly dispose of it afterward.

Step 4: Reattach the Fuel Lines

Once the lines are thoroughly flushed and cleaned, carefully reattach them to the fuel tank. Ensure that all connections are secure and properly sealed to prevent any leaks.

Step 5: Refill the Fuel Tank

After flushing and reconnecting the lines, refill the fuel tank with fresh, clean fuel. Consider using a high-quality fuel with a higher octane rating, such as 98 octane, to help maintain the cleanliness of the fuel system.

Step 6: Test and Monitor

Start the engine and let it run for a while. Observe the engine's performance and check for any leaks or unusual behavior. If the issue persists or you notice any problems, you may need to seek professional assistance or repeat the flushing process.

Remember to wear appropriate safety gear, including gloves and eye protection, when working on your vehicle. Ensure proper ventilation during the flushing process, and always dispose of any fluids responsibly.

Faulty fuel injector signs

There are several signs that may indicate a faulty fuel injector in your Holden Commodore VZ. Fuel injectors play a crucial role in controlling and atomising the fuel that goes into the engine. However, when one or more of these injectors fail or become blocked, it can lead to several issues that can impact the overall performance of your vehicle. Here are some common signs that your Commodore VZ may be experiencing faulty fuel injector problems:

• Rough idling: If your Commodore VZ is idling roughly, it could be a sign that one or more fuel injectors are not functioning properly. This can cause the engine to run unevenly, resulting in a rough and unstable idle.
• Misfiring: Misfiring is another common symptom of faulty fuel injectors. This can be caused by blockages in the injectors or an incorrect amount of fuel being sprayed, leading to incomplete combustion in the engine cylinders.
• Increased fuel consumption: If you notice that your Commodore VZ is consuming more fuel than usual, it could be an indication that the fuel injectors are not delivering the precise amount of fuel required for efficient combustion.
• Difficulty starting the engine: Faulty fuel injectors can make it challenging to start your Commodore VZ. This is often due to blockages or leaks in the injectors, preventing the necessary amount of fuel from reaching the engine during the starting process.
• Engine splutter: An engine splutter is a noticeable jerking or hesitating movement of the engine, which can be caused by fuel delivery issues. If your Commodore VZ's engine splutters, it may be a sign that the fuel injectors are not supplying a consistent and accurate amount of fuel.
• Accelerator hesitation: If you experience a delay or hesitation when you press the accelerator pedal, it could be due to faulty fuel injectors. This hesitation is caused by an insufficient or irregular fuel supply to the engine, affecting the vehicle's acceleration response.

It is important to address these issues promptly and seek expert advice or repairs if necessary. Faulty fuel injectors can have long-term damaging effects on your Commodore VZ's engine if left unattended.

Fuel injector replacement cost

The fuel injector is a critical component of modern automobiles, delivering fuel to the engine in a precise spray pattern and at a specific pressure. Fuel injectors atomize the fuel into tiny droplets, making it easier to burn and creating more efficient combustion. This results in better performance, improved fuel economy, and fewer emissions.

Fuel injectors can become clogged over time, leading to issues such as rough idling or stalling, decreased fuel efficiency, and a fuel smell in the engine oil. While cleaning and maintenance can help, sometimes they need to be replaced.

The cost of replacing fuel injectors can vary depending on several factors, including the type and make of the vehicle, its age, the quality of replacement parts, and labour rates. On average, the cost of replacing fuel injectors ranges from $300 to $900, or even up to $2,500 in some cases, with individual injectors costing under $40 to several hundred dollars each.

It is recommended to get multiple quotes from reliable mechanics before committing to the replacement to ensure an honest assessment and a fair price. While it may be tempting to choose the lowest price, it is important to remember that cutting corners on parts or labour can lead to bigger problems in the future.

In addition to the cost of replacement parts and labour, there may be additional costs for other necessary components, such as an intake manifold gasket and an intake service kit.

For a VZ Commodore, specifically, one source mentions the cost of 1500cc Commodore VN-VZ 5.7lt (V8) Fuel Injectors as being $1,560.

Fuel injector O-ring sealing

Fuel injector O-rings are used to create a seal between the fuel injectors and the fuel rail and intake. They are typically made from fuel-resistant materials such as polyurethane, nitrile rubber, and polytetrafluoroethylene (PTFE). Over time, these O-rings can dry out, deteriorate, and wear down due to the heat and pressure in the fuel system. This can lead to fuel leaks and a lean fuel mixture if the fuel escapes past the seal and doesn't reach the combustion chamber.

If you notice any of the following issues, it may be a sign that your fuel injector O-rings need to be replaced:

• Hard starts
• Misfires
• Poor performance
• Smell of fuel near the top of the engine

To replace the fuel injector O-rings, you will need to purchase a fuel injector seal or O-ring kit, which includes the necessary number and type of seals for a complete fuel injector replacement. The kit typically includes:

• Upper intake manifold set
• Nozzle seal
• Hardware kit
• O-rings in various colours and sizes

When replacing the O-rings, it is important to use fuel-resistant materials to ensure they can withstand the pressures and chemicals in the fuel system.

Frequently asked questions