1985 Mazda RX7 Fuel Pump Location: Complete Guide to Finding and Replacing Your Fuel Pump

If you own a 1985 Mazda RX7 and your car cranks but won't start, or it only runs when you spray starter fluid into the carburetor, the fuel pump is the most likely culprit. The 1985 Mazda RX7 fuel pump is located under the car, near the left rear wheel area, mounted externally on the chassis—not inside the fuel tank like later models. It is an electric external pump, and you can access it by jacking up the rear of the car and looking near the driver's side rear tire.

This guide will walk you through exactly where to find it, how to test it, and how to replace it.

Where is the Fuel Pump on a 1985 Mazda RX7?

The fuel pump on a 1985 Mazda RX7 (also known as the FB or SA22C generation) is mounted externally, not inside the gas tank. Here is the precise location:

  • Under the car, toward the rear
  • On the left (driver's) side, just inside of the left rear wheel area
  • Mounted on a metal shield or bracket near the fuel tank

To get a clear view, you need to jack up the rear of the car securely on jack stands. Once underneath, look near the driver's side rear wheel—you will see a small cylindrical pump attached to a metal shield.

For comparison, later RX7 models (1986-1991) have the fuel pump inside the fuel tank, requiring removal of the rear hatch carpet or dropping the tank. But for the 1985 model, the external pump makes it much easier to access.

How to Tell if Your 1985 RX7 Fuel Pump is Failing

Before you start digging, here are the classic symptoms of a bad fuel pump on a 1985 RX7:

  1. Engine cranks but won't start – This is the most common sign. The car will fire up with starter fluid but die once that fluid burns off.
  2. No humming sound from the rear – When you turn the key to the "ON" position, you should hear the fuel pump make a clicking or humming sound for a few seconds. If you hear nothing, the pump is not getting power or is dead.
  3. Car stalls while driving – A failing pump may work intermittently, causing the engine to cut out.
  4. Low fuel pressure – If the pump is weak, the engine will run lean, hesitate, or lack power.

Step-by-Step: How to Test the 1985 RX7 Fuel Pump

Step 1: Listen for the Pump

Turn the key to the "ON" position (do not start the engine). Get out and listen near the left rear wheel area. You should hear a brief humming or clicking sound for about 2-3 seconds. If you hear nothing, proceed to the next step.

Step 2: Check for Power at the Pump

Locate the pump under the car. The pump has two wires: a Blue with white stripe wire (power) and a Black wire (ground). Use a multimeter to check for 12V power at the connector when the key is in the "ON" position. If you have power but the pump does not run, the pump is bad. If you have no power, the issue is in the electrical circuit.

Step 3: Check the Fuel Pump Relay and Fuse

The fuel pump relay is located under the dash, just inside of the steering column. It has four wires:

  • Two Black with white stripe wires (power into the relay with key on)
  • One Blue with white stripe wire (power out to fuel pump)
  • One Black with yellow stripe wire (coil ground to the ECU)

The fuel pump fuse is a 20 amp fuse located in the under-dash fuse box. It is typically two spots down from the start of a row, with a 15 amp fuse on one side and a 30 amp on the other.

Step 4: Check the Fuel Filter

A clogged fuel filter can mimic a bad fuel pump. The fuel filter is located near the pump, mounted on the same bracket. Replace it if it has been more than a year since it was last changed.

How to Replace the Fuel Pump on a 1985 Mazda RX7

Replacing the external pump on a 1985 RX7 is a straightforward DIY job. Here are the basic steps:

Tools and Parts Needed

  • Jack and jack stands
  • Wrenches (10mm, 12mm, 14mm)
  • Screwdrivers
  • Catch pan for fuel
  • New fuel pump (externally mounted, electric)
  • New fuel hose clamps
  • Safety glasses and gloves

Removal Steps

  1. Disconnect the battery – Always disconnect the negative terminal before working on any fuel system component.
  2. Relieve fuel pressure – Remove the fuel cap and disconnect the fuel line at the carburetor to relieve pressure. Have a catch pan ready.
  3. Jack up the car – Safely raise the rear of the car and secure it on jack stands.
  4. Locate the pump – Find the pump mounted on the metal shield near the left rear wheel.
  5. Remove the mounting shield – Remove the two bolts marked "B" and the nut marked "C" that hold the metal shield in place. Lower the shield.
  6. Disconnect the wires – Cut the fuel pump wire about 1 inch from the pump. You will reconnect the new pump to the chassis wires.
  7. Disconnect the fuel hoses – Remove the hose from the filter to the pump and the outlet hose. Plug the hoses temporarily to prevent fuel spillage.
  8. Remove the old pump – Unbolt the pump from the shield and remove it.

Installation Steps

  1. Install the new pump on the shield – Mount the new pump to the same metal shield using the provided hardware.
  2. Connect the fuel hoses – Connect the hose from the filter to the "IN" fitting on the new pump. Connect the outlet hose to the "OUT" fitting. Use new screw clamps to secure both hoses.
  3. Connect the electrical wires – Strip about 1/2 inch of insulation from the chassis wires. Connect the blue with white stripe chassis wire to the positive wire on the new pump. Connect the black chassis wire to the negative wire on the new pump. Use crimp connectors and wrap with electrical tape for a secure connection.
  4. Reinstall the mounting shield – Lift the pump and shield assembly back into position. Install the bolts and nut you removed earlier. Tighten securely.
  5. Check for leaks – Reconnect the battery, turn the key to "ON" (do not start), and check for fuel leaks at all connections. If no leaks, start the engine and verify the pump is working properly.

Important Safety Tips

Fuel is extremely flammable. Always work in a well-ventilated area, away from open flames, sparks, or any ignition sources. Keep a fire extinguisher nearby. Wear safety glasses and gloves to protect against fuel exposure.

Why You Should Choose a High-Quality Replacement Fuel Pump

When replacing the fuel pump on your 1985 Mazda RX7, do not settle for a cheap, low-quality part. A failing pump can leave you stranded or cause engine damage from a lean fuel mixture.

We recommend the KEMSO brand Fuel Pump for your 1985 Mazda RX7. KEMSO fuel pumps are high-performance, OEM replacement units designed to meet or exceed factory specifications. Each pump is built with premium materials for long-lasting durability and reliable fuel delivery. Best of all, every KEMSO fuel pump comes with a lifetime warranty, giving you complete peace of mind. Whether you are restoring your RX7 to stock condition or building a performance car, KEMSO has the right fuel pump for your needs.

Visit KEMSO Racing today to find the perfect fuel pump for your 1985 Mazda RX7: https://www.kemsoracing.com/

Final Thoughts

The 1985 Mazda RX7 fuel pump is located under the car near the left rear wheel, making it relatively easy to access and replace. If your car cranks but won't start, always start by listening for the pump and checking for power at the connector. A simple test of the relay, fuse, and wiring can save you hours of troubleshooting. And when it comes time to replace the pump, choose a reliable brand like KEMSO to keep your rotary engine running strong for years to come.

For more information and to purchase your replacement fuel pump, visit https://www.kemsoracing.com/


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