How To: Miata Fuel Pump Replacement or Upgrade

Introduction

This tutorial provides a step-by-step guide on how to replace or upgrade the fuel pump in a Mazda MX-5 Miata, specifically for the NA and NB models. Replacing the fuel pump can enhance performance and reliability, and doing it yourself can save you significant money.

Step 1: Gather Necessary Tools and Parts

Before starting the replacement, ensure you have the following tools and parts:

Tools

• Socket set (including a ratchet)
• Screwdrivers (flathead and Phillips)
• Pliers
• Fuel line disconnect tool (optional, but helpful)
• Safety glasses
• Rags or paper towels

Parts

• Replacement fuel pump (options include stock, DW100 for mild upgrades, or DW200 for larger upgrades)
• Fuel pump gasket
• Fuel filter (recommended to replace during this process)

Step 2: Safety First

Ensure you take necessary safety precautions:

• Disconnect the negative battery terminal to prevent any electrical hazards.
• Work in a well-ventilated area to avoid inhaling fuel vapors.
• Keep a fire extinguisher nearby, just in case.

Step 3: Access the Fuel Pump

To access the fuel pump, follow these steps:

1. Locate the Fuel Pump Access Panel:

   • In most Miatas, the access panel is located in the trunk above the fuel tank.

2. Remove the Access Panel:

   • Use a screwdriver to remove any screws or clips securing the panel.
   • Carefully lift the panel to expose the fuel pump assembly.

Step 4: Disconnect Fuel Lines

Before removing the pump, disconnect the fuel lines:

1. Relieve Fuel Pressure:

   • Start the car and let it run until it stalls to relieve pressure in the fuel lines.

2. Disconnect Fuel Lines:

   • Use the fuel line disconnect tool if necessary, and carefully detach the fuel lines from the pump.

Step 5: Remove the Fuel Pump Assembly

Now you can remove the fuel pump assembly:

1. Unscrew the Pump Assembly:

   • Locate and remove the screws or bolts holding the pump assembly in place.

2. Lift Out the Assembly:

   • Carefully lift the entire assembly out of the tank, noting how it is positioned for reinstallation.

Step 6: Replace the Fuel Pump

With the assembly out, you can now replace the fuel pump:

1. Remove the Old Pump:

   • Detach the old pump from the assembly by removing any clips or screws.

2. Install the New Pump:

   • Secure the new pump in place, ensuring it is properly seated.

3. Replace the Gasket:

   • Install a new gasket to prevent leaks.

Step 7: Reinstall the Fuel Pump Assembly

Now it's time to put everything back together:

1. Reinsert the Assembly:

   • Carefully lower the fuel pump assembly back into the tank, aligning it as it was initially.

2. Secure the Assembly:

   • Use screws or bolts to secure the assembly in place.

3. Reconnect Fuel Lines:

   • Reattach the fuel lines, ensuring they are tight to avoid leaks.

Step 8: Test the New Fuel Pump

With everything reassembled, it's time to test:

1. Reconnect the Battery:

   • Reattach the negative terminal to the battery.

2. Turn the Ignition On:

   • Turn the key to the "on" position (not starting the engine) to prime the fuel system.

3. Check for Leaks:

   • Inspect the area around the fuel pump for any signs of leakage.

4. Start the Engine:

   • If everything looks good, start the engine and listen for the new pump operating smoothly.

Conclusion

You have successfully replaced or upgraded the fuel pump in your Mazda MX-5 Miata. Regular maintenance of your fuel system can enhance performance and reliability. If you encounter any issues, consult a professional mechanic or revisit this guide for troubleshooting tips. Happy driving!