Replacing Fuel Lines In Your S14: A Step-By-Step Guide

Replacing the fuel lines on an S14 can be a complex task, but it is doable as a DIY project. The first step is to determine the size of the fuel lines that need to be replaced. The stock fuel lines on an S14 are typically around 5/16 or 3/8 in diameter. It is important to use fuel injection lines or ethanol-compatible lines to handle the pressure and avoid leaks. When replacing the fuel lines, there are a few different options for the type of lines and fittings to use. Some popular choices include stainless steel, aluminum, or braided lines with Teflon or rubber inner liners. It is also important to consider the fittings and whether to use compression, flare, or brazed/TIG connectors. Some people choose to upgrade their fuel lines for safety, reliability, or to accommodate an adjustable fuel pressure regulator and fuel pressure sender. When replacing the fuel lines, it may be necessary to drop the fuel tank, but there is usually an access panel under the carpet or in the trunk that provides access to the fuel lines.

Braided hose clamps vs stainless steel hard lines

Braided hose clamps and stainless steel hard lines are two options for fuel lines. Braided hose clamps are attached to braided hoses, which are typically made of stainless steel and are known for their durability and high-pressure resistance. Braided hoses are often used in conjunction with hard lines, as they provide flexibility and allow for movement. On the other hand, stainless steel hard lines are rigid and require bending to fit specific applications. They are more challenging to work with and are less friendly if adjustments are needed.

When choosing between braided hose clamps and stainless steel hard lines, it is essential to consider the specific requirements of your project. Braided hose clamps offer ease of installation and flexibility, making them suitable for connections and areas that need movement. However, they may not provide the same level of durability and pressure resistance as stainless steel hard lines.

Stainless steel hard lines, on the other hand, offer superior strength and are often chosen for their longevity. They are less likely to leak and are compatible with various fittings, such as compression or flare fittings. Hard lines are commonly used for fuel lines along frame rails, providing a neat and durable solution. However, they require careful bending to match the specific application, and the bending process can be challenging.

In some cases, a combination of both options may be used. Braided hoses can be attached to hard lines using compression fittings or other adapters, providing a balance between flexibility and durability. It is recommended to use fuel injection clamps or similar high-quality clamps to secure the connections and prevent leaks.

Additionally, it is worth noting that fuel line kits are available, offering a complete solution for upgrading fuel lines. These kits typically include high-end components, such as black aluminum fittings and stainless steel-reinforced hoses, providing a stealthy and reliable option for enthusiasts. When considering fuel lines, it is crucial to prioritize safety and ensure that the chosen option meets the required specifications, such as pressure ratings and compatibility with fuel types.

Fuel line sizing

When it comes to fuel line sizing for the Nissan 240SX S14, there are a few things to consider. The diameter of the fuel line is important, and for the S14, it is typically 5/16". It is also essential to use a fuel line that is compatible with the type of fuel being used. For example, if using ethanol fuel, it is crucial to use a fuel line that is rated for ethanol, such as the Goodridge 811/910, Earls Ultra-Flex 650, or XRP HS-79.

Another consideration is the material of the fuel line. Some options include stainless steel, aluminium, or rubber. Stainless steel fuel lines are often more expensive and challenging to work with, but they are durable and compatible with all fuel types. Aluminium fuel lines are more commonly used and are adequate for most applications. Rubber fuel lines are also an option and can be purchased by the foot at most parts stores. However, it is important to ensure that the rubber fuel line is compatible with the type of fuel being used.

Additionally, when choosing a fuel line, it is essential to consider the fittings and connectors. Fittings are typically made of aluminium or steel and come in various sizes, such as -6 or -8. It is important to ensure that the fittings are compatible with the fuel line and the fuel type. Connectors can be compression fittings, flare fittings, or brazed/TIG welded connections. When attaching AN fittings to hard lines, it is recommended to use flare fittings or brazed/TIG welded connections.

Finally, it is worth considering the length of the fuel line. It is generally recommended to use long runs of hard steel fuel lines for safety and reliability, with short runs of flexible fuel lines for easy access and maintenance.

Fuel line materials

Fuel lines can be made from a variety of materials, including metal, rubber, nylon, copper, and plastic.

Metal Fuel Lines

Metal fuel lines are the most durable option and are generally compatible with all fuel types. They are usually made from stainless steel, coated steel, or aluminium. Metal lines are also the most difficult to fabricate and are generally more expensive than rubber or braided lines. They are also heavier than other options, which can be a consideration for some vehicles.

Rubber Fuel Lines

Rubber fuel lines are flexible and easy to install, making them ideal for tight or hard-to-reach spaces. They are typically connected using barbed fittings and fuel line hose clamps. However, rubber lines have some downsides. They start degrading as soon as they come into contact with fuel and are susceptible to cuts and nicks. They also leak fuel vapours, which can be a problem in enclosed spaces.

Braided Fuel Lines

Braided fuel lines are typically made from a metal or synthetic fibre braid wrapped around a rubber core. They are more durable than plain rubber lines and are compatible with a wide range of fuels. However, they are generally less flexible than rubber lines and can be prone to leaks if the braid becomes damaged. Braided lines are also more expensive than plain rubber lines.

PTFE-Lined Fuel Lines

PTFE-lined fuel lines have an inner layer of PTFE (polytetrafluoroethylene), a synthetic fluoropolymer, which is coated with a layer of braided stainless steel or other metal. These lines are very durable and resistant to wear, heat, and chemical damage. They are also flexible and generally compatible with a wide range of fuels and chemicals. However, they are typically the most expensive option and require special fittings.

Nylon Tubing

Nylon tubing is a good option for fuel line repairs on a budget. It is lighter and more durable than rubber fuel hose and does not perish like rubber. However, it melts at lower temperatures and cannot be repaired as easily.

Choosing the Right Fuel Line

The type of fuel line you choose depends on your specific application. Metal lines are generally the most durable and compatible option, but they are also the most expensive and difficult to fabricate. Rubber and braided lines are more flexible and easier to install but are more susceptible to degradation and leaks. PTFE-lined lines offer the best performance in terms of durability and compatibility but are the most expensive and require special fittings. For fuel line repairs on a budget, nylon tubing can be a good alternative to rubber or braided lines.

Fuel line fittings

When it comes to fuel line fittings for your S14, there are a few options to consider. The type of fitting you choose will depend on your specific requirements and preferences. Here are some detailed instructions and considerations for fuel line fittings:

Types of Fittings

• Aluminum vs Stainless Steel: Aluminum fittings, such as those included in the Chase Bays Fuel Line Kit, are commonly used and considered more than adequate by many. They are also anodized, making them compatible with ethanol-blended fuel. Stainless steel fittings, on the other hand, are typically intended for more specialized applications and are harder to find. They are also more expensive and heavier.
• Compression vs Flare Fittings: When attaching fittings to hard lines, you can use compression fittings or flare fittings. Compression fittings are tighter and more secure, while flare fittings are easier to work with and can provide a leak-free seal. Flare fittings require the use of a flaring tool to create a 37-degree flare for a proper seal.
• Brazing/TIG Welding: Another option is to braze or TIG weld the fittings directly onto the hard lines. This method provides a strong and secure connection but may require specialized skills and equipment.

Fuel Line Materials

The type of fuel line material you use will also impact the choice of fittings. Here are some common fuel line materials and their considerations:

• Rubber Hose: Rubber hoses are commonly used for fuel lines and can be found at most auto parts stores. When using rubber hoses, it is important to use fuel injection clamps or pinch clamps for a secure connection.
• Braided Stainless Steel: Braided stainless steel lines, such as the Sikky 240sx S14 LSx Fuel Filter Kit, offer high durability and can sustain very high pressures. They are more expensive but provide added safety, especially in the event of an impact.
• Teflon/PTFE: Teflon or PTFE (polytetrafluoroethylene) lines are compatible with all types of fuel, including gasoline and alcohol. They are lightweight, flexible, and easy to work with. However, they may be more expensive than rubber or stainless steel lines.

Additional Considerations

• Fuel Type: Consider the type of fuel you will be using. If you plan to use ethanol-blended fuel or E85, ensure that your fuel lines and fittings are compatible and rated for these fuels.
• Pressure and Flow: If you have a high-performance engine or plan to upgrade, ensure that your fuel lines and fittings can handle the required fuel pressure and flow rate. Larger lines, such as -8AN, may be necessary for high-horsepower applications.
• Cost and Availability: Some fittings and line materials, such as stainless steel, can be more expensive and harder to find. Consider your budget and the availability of parts before making your decision.
• Ease of Installation: Some fittings, such as compression fittings, may be easier to work with than others. Consider your level of mechanical skill and the tools required for installation.

Fuel line routing

The fuel line routing in an S14 can be a complex process, and it is important to ensure that the lines are installed correctly to avoid leaks and ensure proper fuel delivery. Here is a detailed guide on fuel line routing for the S14:

First, it is important to determine the type of fuel line to use. The stock fuel lines in the S14 are typically adequate for most applications, with a size of about -5 AN. However, if you are upgrading the fuel system or experiencing leaks, you may need to replace them with larger lines such as -6 AN or 3/8" lines. It is also essential to use fuel injection-rated lines if you plan to use higher pressure. These lines are designed for newer fuel systems and can handle higher pressures. Additionally, ensure that the lines are compatible with the type of fuel you will be using, such as E85 or ethanol-blended gasoline.

Next, consider the materials used for the fuel lines. Stainless steel or aluminum are common choices, with aluminum being more lightweight and adequate for most applications. Stainless steel is more durable but may be harder to bend and is more expensive. For the fittings, anodized aluminum is a popular choice, but it is crucial to ensure they are compatible with the type of fuel line you are using. Stainless steel fittings are overkill for most applications but may be necessary if you are using stainless steel hard lines to prevent corrosion with ethanol-blended fuel.

When attaching the fittings to the hard lines, you have a few options. You can use compression fittings, flare fittings, or braze/TIG weld the fittings onto the hard lines. Compression fittings are easy to install, while flare fittings provide a secure connection and are less likely to leak. Brazing or TIG welding the fittings will result in the most durable connection but requires more specialized equipment and skills.

Finally, when routing the fuel lines, ensure that they are securely mounted and tied down to prevent abrasion and rubbing against other components. Stainless steel braided lines are more durable but can act like a file and wear through other components they rub against. Nylon or Kevlar braided lines are more flexible, lightweight, and less likely to cause abrasion. Use fuel line clamps to secure the lines, and consider using OEM clamps or pinch clamps for a more secure hold.

Frequently asked questions