Upgrading The Mk1 Fuel Tank: Enhancing Performance And Safety

Replacing the fuel tank in your car can be a daunting task, but it is necessary to ensure the safety and proper functioning of your vehicle. The process involves first identifying the source of the fuel leak, which could be from the tank or any connected hoses. Once the issue is diagnosed, the next steps include safely removing the old tank and installing a new one. This may require some mechanical knowledge and skills, as well as specific tools and equipment. It is important to take precautions when working with fuel systems to avoid any potential hazards.

Fuel leaks

Another potential cause of fuel leaks is loose or improper clamps on the fuel lines. It is important to use the correct type of clamps, such as fuel hose clamps, as regular jubilee clamps can squash the hose in one area and cause leaks. Checking and tightening the clamps on the fuel lines can often resolve this issue.

In some cases, the fuel tank itself may be leaking. This can be due to holes or corrosion in the tank, which can occur over time, especially if the tank has been left empty for extended periods. If the tank is leaking, it may need to be repaired or replaced.

Additionally, issues with the gravity valve or breather system can cause fuel leaks. A blocked or malfunctioning gravity valve can lead to pressure build-up in the tank, forcing fuel out through the breather or vent. Checking and cleaning the breather system and gravity valve can help resolve this issue.

It is important to thoroughly inspect the fuel system and identify the source of the leak before attempting any repairs or replacements. In some cases, it may be necessary to remove the fuel tank for a more thorough inspection.

Fuel pump issues

The Mk1 Golf has two fuel pumps: the main one underneath the car and a secondary 'lifter' (or 'in-tank') fuel pump within the actual fuel tank.

Car Turns Over But Isn't Starting

If your car is turning over but not starting, it could be due to a faulty fuel pump. The fuel pump is responsible for delivering fuel from the tank to the engine, and if it's not working properly, the engine may not be getting the fuel it needs to start. Try checking the fuel pump for any signs of damage or wear and replace it if necessary.

Engine Stops When Braking or Accelerating

If your engine stops unexpectedly while you are braking or accelerating, it could be due to a faulty fuel pump. This issue can be caused by a variety of factors, including a clogged fuel filter, a faulty fuel pump relay, or a problem with the fuel pump itself. Check the fuel pump for any signs of damage or wear and replace it if necessary. It is also recommended to check the fuel filter and fuel pump relay to ensure they are functioning properly.

Engine Sputters and Stops After Running for a Short Period

If your car's engine sputters and stops after running for a short period of time, it could be due to an overheating fuel pump. This issue is often caused by a clogged fuel filter or a faulty fuel pump. Check the fuel pump for any signs of damage or wear and replace it if necessary. It is also recommended to check and replace the fuel filter if it is clogged.

Pump Makes Grinding or Vibrating Noises

If your fuel pump is making unusual grinding or vibrating noises, it could be a sign that it is failing. These noises could indicate that the pump's motor is struggling to function properly, which can lead to reduced fuel pressure and flow. It is recommended to replace the fuel pump as soon as possible to avoid further damage or performance issues.

Fuel Pump Not Producing Suction

If your fuel pump is not producing any suction, it could be due to a blockage in the fuel line or a faulty pump. Check the fuel line for any signs of blockage and clear it if necessary. Additionally, inspect the pump for any damage or wear and replace it if needed.

Fuel Pump Relay or Fuse Issues

The fuel pump relies on electrical power to function, and issues with the relay or fuse can impact its operation. If the fuel pump is not priming when the ignition is turned on, check the relay and fuse to ensure they are in proper working condition. Replace them if necessary.

Replacing the entire fuel system

Assess the Condition of the Fuel System: Before embarking on a full replacement, it's essential to thoroughly inspect and diagnose the issues with your current fuel system. This may involve checking for leaks, corrosion, or damage to the fuel tank, fuel lines, fuel pump, and other components. It's important to identify all the problematic parts to determine if a complete replacement is indeed necessary.

Source Quality Replacement Parts: When replacing the entire fuel system, it's crucial to source high-quality replacement parts that are compatible with your vehicle. This includes finding a fuel tank that is specifically designed for your car model and year. Ensure that the replacement fuel tank is free of defects and made from durable materials. Additionally, consider purchasing new fuel lines, a new fuel pump, and any other necessary components to ensure optimal performance and longevity.

Repair or Replace the Fuel Tank: If your fuel tank is the main source of issues, you have several options. You can attempt to repair and refurbish the existing tank by cleaning it, rebuilding internal components, and sealing it. Alternatively, you can opt for a replacement fuel tank. When choosing a replacement tank, pay attention to the inclusion of components like baffles, surge tanks, and proper fuel pickup systems to ensure adequate fuel delivery and vehicle performance.

Replace Fuel Lines and Fuel Pump: Corroded or damaged fuel lines are a common issue, especially in older vehicles. When replacing the fuel lines, consider using pre-bent lines or bending your own lines with the appropriate tools. Avoid using flexible fuel hoses or braid stainless steel lines as they can compromise safety and performance. Additionally, follow the recommended procedures to replace the fuel pump, ensuring all connections are secure and properly sealed.

Test and Refill the System: Once you've replaced all the necessary components, it's important to test the system for leaks and ensure that all connections are secure. Start the vehicle and check for any signs of fuel leaks. If everything appears to be in order, refill the fuel tank and test-drive the vehicle to ensure that the fuel system is functioning correctly.

While replacing the entire fuel system can be a complex task, it may be the best solution in certain situations. Always refer to vehicle-specific repair manuals and seek guidance from experienced mechanics or automotive forums when undertaking such comprehensive repairs.

Cost-effectiveness of replacement vs. repair

The cost of replacing a fuel tank depends on the type of car you have. For instance, a new fuel tank for a Honda Civic costs between $400 to $600, while an equivalent part for a BMW 7 Series costs nearly $1,600. The average cost of replacing a fuel tank is between $700 and $2,500, with labour costs estimated between $264 and $333 and parts priced between $1,224 and $1,265.

While it is possible to repair a fuel tank, it is not recommended due to safety concerns. Fuel tanks are still extremely flammable when removed, and repairing one incorrectly can lead to the entire shop catching on fire. Therefore, it is generally advised to replace the fuel tank entirely.

If you are looking for a more cost-effective option, you may want to consider repairing your fuel tank. However, it is important to note that repairing a fuel tank can be dangerous, especially if you do not have the necessary expertise. One mechanic cautioned that he has seen viral clips of technicians setting their shops on fire while attempting to repair fuel tanks.

Additionally, repairing a fuel tank may not always be successful. In one instance, a forum user shared that they tried to fix their fuel tank by soldering the pickup tube, but the fix eventually failed as the hose rotted away after a few months.

On the other hand, replacing a fuel tank can be costly, and finding a suitable replacement may be challenging. Aftermarket fuel tanks are rare, and used tanks come with the risk of eventually developing the same issues as the original tank, especially if the car has historical fuel tank problems.

Considering the risks and challenges associated with both options, it is essential to carefully weigh the pros and cons of each before making a decision.

Cleaning the fuel tank

Inspecting and Cleaning the Fuel Tank:

• Before removing the fuel tank, it is recommended to inspect it for any signs of rust or corrosion. You can use a telescopic pen-type magnet through the sender opening to check for rust.
• If the tank is dirty but not severely rusted, you may be able to clean it without removing it. One method is to use a drill pump to flush a cleaning solution through the tank. Some people recommend using cider vinegar, while others suggest a fuel-resistant cleaning solution.
• Another approach is to create a recirculating system using a car battery, a fuel pump, and some pipes. This allows you to "hoover" debris out of the tank and filter the fuel back into the filler neck.
• If the tank is heavily soiled, it is best to remove it for a thorough cleaning. This involves disconnecting the fuel pump, hoses, and other components, and then carefully working the tank out through the opening.
• Once the tank is removed, you can more easily access and scrub the interior. You may need to cut inspection plates to reach all areas of the tank.
• For extremely dirty or rusty tanks, some people choose to send them to specialist shops for cleaning and refurbishment. These shops will open the tank, clean and repair it, and then seal the inside and outside.

Finding a Replacement Fuel Tank:

• If your Mk1 Golf fuel tank is beyond repair or you prefer to replace it, there are a few options to consider:
• OEM (Original Equipment Manufacturer) tanks: These are direct replacements from Volkswagen and are made to the same specifications as the original. However, they may be difficult to find and expensive.
• Aftermarket tanks: There are mixed reviews about the quality of aftermarket fuel tanks. Some people have reported issues with fuel starvation and missing internal components. It is recommended to inspect the tank carefully before purchasing.
• Used OEM tanks: Another option is to search for a decent second-hand OEM tank. While it may take some effort to find one in good condition, it can be a more affordable alternative.

Remember to refer to your vehicle's specific repair manual and follow safety precautions when working on any fuel system components.

Frequently asked questions