Installing A Fuel Pressure Regulator In Your Wrx

Installing a fuel pressure regulator in a WRX is a relatively straightforward process, but it's important to follow the correct steps to ensure a successful installation. This guide will walk you through the process of installing a fuel pressure regulator in your WRX, including the tools and parts you'll need, step-by-step instructions, and helpful tips to make the process go smoothly. It is important to note that working on fuel systems can be dangerous, so it is recommended that you wear safety goggles and exercise caution when performing this installation.

Removing the old fuel pressure regulator

To remove the old fuel pressure regulator from your WRX, you will need to take a few careful steps to ensure the process is safe and effective. Here is a detailed guide to help you through the removal process:

Prepare Your Vehicle

Before you begin, it is important to wear safety goggles as you will be working with fuel lines. Start by removing the E/G fuse from the fuse box and cranking the engine a few times to depressurise the fuel lines. This is an important safety measure to prevent any accidental fuel spray or leakage.

Locate the Fuel Pressure Regulator

The fuel pressure regulator (FPR) is located next to the air intake box on the passenger side of your WRX. It is connected to a vacuum line that leads to the intake manifold.

Remove the Fuel Pressure Regulator

To remove the FPR, you will need to:

• Remove the two 10mm bolts securing the FPR.
• Loosen the clamp on the fuel line connected to the FPR.
• Slowly wiggle the FPR out, being careful not to damage the vacuum line connected to the intake manifold.

Secure the Vacuum Line

The most important step during the removal process is to use zip ties to secure the vacuum line. This is a well-known problem area, and failure to secure the line properly could result in it popping off, leading to potential engine damage.

Replace the O-Ring

Inspect the O-Ring for any damage or wear and replace it if necessary. It is important to use a fuel-compatible O-ring, such as one made of Viton, to ensure it can withstand the fuel without failing.

By following these steps, you will be able to safely and effectively remove the old fuel pressure regulator from your WRX, preparing you for the next step of installing a new one.

Installing the new fuel pressure regulator

Installing a new fuel pressure regulator (FPR) can be a tricky process, but with care and attention, it is possible to DIY. This guide will take you through the steps to safely install a new FPR in your WRX.

Firstly, ensure you are wearing safety goggles as you will be working with fuel lines. Remove the E/G fuse from the fuse box and crank the engine a few times to depressurise the fuel lines. The FPR is located next to the air intake box on the passenger side. Remove the two 10mm bolts and loosen the clamp on the fuel line. Now, carefully wiggle the FPR out, being mindful not to damage the vacuum line connected to the intake manifold.

The next step is crucial: use zip ties to secure the vacuum line. This is a well-known problem area, and failure to secure the line could result in engine damage. Replace the O-ring if necessary. Now, you can install the new FPR, ensuring the vacuum line is secure.

Finally, you can reconnect the fuel line and bolts, being careful not to over-tighten the bolts. If there is a leak, you may have damaged the O-ring, so check this and try again. Now, you can start the engine and check for any leaks.

It is important to note that this guide is generic and may not cover all specific requirements for your vehicle. Always refer to a qualified mechanic if you are unsure about any steps or procedures.

Securing the vacuum line

To secure the vacuum line, you must first remove the FPR (fuel pressure regulator) by removing the two 10mm bolts and loosening the clamp on the fuel line. Slowly wiggle the FPR out, being careful not to damage the vacuum line, which is connected to the intake manifold. This is the most important step of the installation process: use zip ties to secure the vacuum line, as this will prevent it from popping off, a well-known problem that can cause your engine to blow up. Once the vacuum line is secure, you can replace the O-ring if necessary and install the new FPR.

It is also important to wear safety goggles during this process, as you will be working with fuel lines. Before beginning, depressurise the fuel lines by pulling the E/G fuse from the fuse box and cranking the engine a few times.

When securing the vacuum line, be sure to handle the fuel lines with care and avoid over-tightening the bolts, as this can damage the O-ring. It is recommended to use a small dab of lube or dish soap on the O-ring before installation. Additionally, ensure that you are using fuel O-rings made from Viton, as regular rubber O-rings will fail when used to seal fuel.

By following these steps, you can securely install the vacuum line and prevent any potential issues with the fuel pressure regulator in your WRX.

Replacing the O-ring

To replace the O-ring, you will need to purchase a new O-ring. This can be found at most hardware stores or online. The O-ring needs to be the correct size and made of Viton, as regular rubber O-rings will not work with fuel.

Once you have the new O-ring, locate the fuel pressure regulator (FPR) on the passenger side of the car, next to the air intake box. Remove the FPR by loosening the clamp on the fuel line and gently wiggling it out. Be careful not to damage the vacuum line connected to the intake manifold.

Now, you can replace the O-ring. It is recommended to put a small amount of lubricant or dish soap on the O-ring before putting it in place. Make sure the O-ring is seated correctly and securely before reassembling the FPR.

Finally, reattach the FPR by sliding it back into place and tightening the clamp on the fuel line. Ensure that the vacuum line is securely attached to the intake manifold. Do not over-tighten the bolts, as this can damage the new O-ring.

Tuning the fuel pressure

Step 1: Understanding the Fuel System

Before making any adjustments, it's crucial to understand how the fuel system in your WRX works. The fuel pressure regulator (FPR) plays a vital role in maintaining the correct fuel pressure, ensuring that the fuel injectors receive the right amount of fuel at the appropriate pressure.

Step 2: Selecting the Right Fuel Pressure Regulator

Choosing a suitable FPR for your WRX is essential. Aftermarket adjustable FPRs, such as the Tomei Fuel Pressure Regulator, offer greater control over fuel pressure and can be tuned to match your specific setup.

Step 3: Installation

Installing the FPR involves removing the OEM damper and FPR assembly. You will need additional parts, including fuel hoses, fuel hose clamps, brass hose menders, and STI fuel supply and return dampers. Follow the installation guide provided with your FPR for a proper fit.

Step 4: Connect the Fuel System Components

Connect the '06 supply side damper to the original fuel supply hose and then connect the other side of the damper to the inlet of the fuel rail. Ensure that the fuel rail outlet is connected to the FPR inlet, and the FPR outlet is connected to the return damper. Finally, connect the return damper to the return hose.

Step 5: Adjusting the Fuel Pressure

Now, it's time to adjust the fuel pressure to suit your needs. The OEM fuel pressure for the WRX is typically set at 43.5 psi. However, you can deviate from this setting to match your fuel requirements. Use a fuel pressure gauge to monitor the pressure and make adjustments as needed.

Step 6: Tuning the Engine Load Compensation Tables

After setting the desired fuel pressure, you may need to adjust the engine load compensation tables of your tune. This step ensures that the engine's performance matches the new fuel pressure settings.

Step 7: Safety Precautions

Always wear safety goggles when working with fuel lines. Before beginning any work, depressurize the fuel lines by pulling the E/G fuse from the fuse box and cranking the engine a few times. Additionally, ensure that all connections are secure, especially the vacuum line, to prevent it from popping off.

Step 8: Troubleshooting

If you encounter issues, such as a rough idle or lean running, double-check the connections to the FPR. Ensure that the fuel rail outlet is connected to the FPR inlet and the fuel return hose to the FPR outlet. Incorrect connections can lead to improper fuel flow and affect the engine's performance.

Step 9: Fuel System Maintenance

Keep your fuel system well-maintained by regularly inspecting and replacing vital components. This includes the fuel pump, fuel filters, and fuel lines. Ensure that all connections are secure and free from leaks.

Step 10: Monitoring and Optimization

Continuously monitor your WRX's performance and fuel efficiency after tuning the fuel pressure. Fine-tune the settings as needed to achieve the desired balance between performance and fuel economy.

Frequently asked questions