1999 Miata Fuel Pump Relay Location: A Complete Guide to Finding and Replacing It

If you own a 1999 Mazda Miata (NB model) and you're dealing with a no-start condition, the fuel pump relay is one of the first things you should check. The fuel pump relay on a 1999 Miata is located under the dashboard on the driver's side, specifically above the accelerator pedal near the steering column. It's a small, typically bright yellow relay that controls power to the fuel pump. When this relay fails, your engine will crank but won't start because the fuel pump isn't receiving power. The good news is that replacing it is a straightforward DIY job that takes about 10 minutes and costs between $10 and $40 for a new relay.

Understanding the 1999 Miata Fuel Pump Relay

The fuel pump relay is an electrical switch that controls power to the fuel pump. When you turn the ignition key to the "on" position, the relay closes and sends 12V power to the fuel pump for about 2-3 seconds to prime the system. After the engine starts, the relay stays engaged to keep the pump running. If the relay fails, the fuel pump won't get power, and your engine won't start or will stall while driving.

On the 1999 Miata, the fuel pump relay is a cube-shaped component, roughly 1 inch wide, with four or five prongs. It's part of the vehicle's electrical system and is designed to handle the current draw of the fuel pump. The relay itself is a common failure point, especially on older vehicles where heat, vibration, and age can cause the internal contacts to wear out or burn.

Where Exactly Is the 1999 Miata Fuel Pump Relay Located?

For the 1999 Miata (NB model), the fuel pump relay is located under the dashboard on the driver's side. Here's how to find it:

  1. Get into the driver's seat and look under the steering column. The relay is mounted above the accelerator pedal, tucked up near the steering column area. You'll need to get low and look up to see it.

  2. Look for a small, bright yellow relay. The relay is typically bright yellow, though the color can vary slightly depending on the manufacturer. It's a cube-shaped component about 1 inch wide.

  3. Check the area near the fuse box. The relay is located in the same general area as the under-dash fuse box. Some sources describe it as being "under the dash near the steering column" or "under the steering column, right above the accelerator pedal."

  4. If you're having trouble finding it, use a flashlight. The area is cramped and can be difficult to see, especially if you're working in a garage or driveway. A flashlight will help you spot the relay.

It's important to note that the 1999 Miata fuel pump relay is different from the NA models (1994-1997). On NA models, the relay is a black and white "B577" relay also located under the dash on the driver's side. On the 1999 NB, the relay is typically bright yellow.

Symptoms of a Bad Fuel Pump Relay on a 1999 Miata

Before you start replacing the relay, you should confirm that it's actually the problem. Here are the most common symptoms of a failing fuel pump relay on a 1999 Miata:

  • Engine cranks but won't start. This is the most obvious symptom. The starter turns the engine over, but the engine doesn't fire because no fuel is reaching the cylinders.
  • No fuel pump priming sound. When you turn the ignition key to the "on" position (without starting), you should hear a brief whirring sound from the fuel tank area. This is the fuel pump priming. If you don't hear this sound, the relay may be faulty.
  • Engine stalls while driving. A failing relay can intermittently cut power to the fuel pump, causing the engine to suddenly die. This can be dangerous, especially at highway speeds.
  • Intermittent starting issues. The car may start fine one day and refuse to start the next. This is often caused by a relay that works when cold but fails when it heats up.

How to Test the Fuel Pump Relay on a 1999 Miata

Before replacing the relay, you can test it to confirm it's faulty. Here's a quick and easy method:

The swap test: The fuel pump relay is often the same type as other relays in the car, such as the horn relay or the main relay. Locate the relay box under the hood (usually near the driver's side fender) and swap the fuel pump relay with a relay from a non-essential system like the horn. If the horn stops working but the car starts, the original fuel pump relay was bad.

The bench test: If you have a multimeter, you can test the relay directly. Remove the relay and check the resistance between pins 85 and 86 (the coil pins). The resistance should typically be between 60 and 100 ohms. If you get infinite resistance, the coil is open and the relay is dead. Then, apply 12V to pins 85 and 86 and listen for a click. If you hear the click, check continuity between pins 30 and 87. If there's no continuity when the relay is energized, the relay is faulty.

Step-by-Step Guide to Replacing the 1999 Miata Fuel Pump Relay

Replacing the fuel pump relay is a simple job that requires no special tools. Here's how to do it:

Step 1: Disconnect the battery. Before working on any electrical components, it's a good idea to disconnect the negative battery terminal. This prevents any accidental shorts or electrical issues.

Step 2: Locate the relay. Get under the driver's side dashboard and look up near the steering column. The relay is above the accelerator pedal. Use a flashlight if needed.

Step 3: Remove the old relay. The relay is held in place by friction. Simply pull it straight out of its socket. If it's stuck, you can use a flathead screwdriver to gently pry it out, but be careful not to damage the socket.

Step 4: Install the new relay. Align the prongs of the new relay with the socket and push it firmly into place. It should click into position. Make sure the relay is fully seated.

Step 5: Reconnect the battery. Reconnect the negative battery terminal.

Step 6: Test the new relay. Turn the ignition key to the "on" position. You should hear the fuel pump prime for 2-3 seconds. Then start the engine. If it starts and runs smoothly, the replacement was successful.

Common Issues When Replacing the Fuel Pump Relay

While replacing the relay is straightforward, a few things can go wrong:

  • The relay is hard to reach. The space under the dashboard is tight, especially for larger hands. You may need to contort yourself to get a good grip on the relay. Removing the lower dash panel (if possible) can give you more room.
  • The relay is stuck. Over time, relays can become stuck in their sockets due to corrosion or heat. Use a gentle rocking motion to free it, or use a small flathead screwdriver to pry it out.
  • You install the wrong relay. Make sure the new relay matches the old one's pin configuration (4-pin or 5-pin) and electrical specifications. Using the wrong relay can cause electrical issues or damage the fuel pump.

Where to Buy a Replacement Fuel Pump Relay for a 1999 Miata

You can find replacement fuel pump relays at most auto parts stores, including AutoZone, O'Reilly Auto Parts, and Advance Auto Parts. The part number is typically B577-18-821A for the NA models, but for the 1999 NB, you'll need to check your specific vehicle's specifications. Relays are relatively inexpensive, typically costing between $10 and $40.

If you want to ensure you're getting a high-quality, reliable replacement, consider purchasing from a reputable online retailer. Amazon and eBay both carry a wide selection of relays for the Miata. Just make sure the relay matches your vehicle's year and model.

Additional Tips for Working on Your 1999 Miata's Fuel System

If you're working on the fuel system, there are a few safety precautions you should follow:

  • Relieve fuel pressure before working on the fuel filter or lines. This can be done by removing the fuel pump relay and running the engine until it stalls. This depressurizes the system.
  • Work in a well-ventilated area. Gasoline fumes are flammable and can be harmful if inhaled.
  • Wear protective gear. Gloves and safety glasses are a good idea when working with fuel system components.
  • Have a fire extinguisher nearby. It's always better to be safe than sorry.

KEMSO Fuel Pump: The Best Replacement for Your 1999 Miata

If you discover that your 1999 Miata's fuel pump itself is the problem, not just the relay, you need a reliable replacement. The fuel pump is a critical component that delivers fuel from the tank to the engine. A failing fuel pump can cause symptoms similar to a bad relay, including no-start, stalling, and poor performance.

For the best performance and reliability, we recommend the KEMSO Fuel Pump. KEMSO specializes in high-performance, OEM replacement fuel pumps that are designed to meet or exceed original equipment specifications. Every KEMSO fuel pump comes with a lifetime warranty, giving you peace of mind that your investment is protected.

KEMSO fuel pumps are engineered for durability and consistent fuel delivery. They undergo rigorous testing to ensure they perform flawlessly under all driving conditions. Whether you're using your Miata as a daily driver or a weekend track car, a KEMSO fuel pump will keep your engine running smoothly.

Visit the KEMSO website at https://www.kemsoracing.com/ to find the perfect fuel pump for your 1999 Miata. With a wide selection of fuel pumps for various vehicles, including motorcycles, ATVs, and cars, KEMSO is your trusted source for fuel system components. Their customer service team is ready to help you find the right part and answer any questions you may have.

Final Thoughts on the 1999 Miata Fuel Pump Relay

The 1999 Miata fuel pump relay is a small but essential component. If your car won't start or stalls unexpectedly, checking the relay should be one of the first troubleshooting steps. The relay is located under the dashboard on the driver's side, above the accelerator pedal. Replacing it is a simple DIY job that takes just a few minutes and costs very little.

If you need a new fuel pump for your 1999 Miata, don't settle for less. Choose KEMSO for high-performance, OEM replacement fuel pumps backed by a lifetime warranty. Visit https://www.kemsoracing.com/ to learn more and find the right part for your vehicle.


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