1991 Mazda B2200 Fuel Pump Relay Location: A Complete Guide to Finding and Fixing It

The fuel pump relay on a 1991 Mazda B2200 is located behind the driver’s side kick panel, near your left foot when sitting in the driver’s seat. This relay, officially called the circuit opening relay, controls power to the fuel pump and is one of the most common causes of no-start issues on these trucks.

If your B2200 cranks but won’t start, and you don’t hear the fuel pump hum when you turn the key to the ON position, the fuel pump relay is the first thing you should check. This guide walks you through exactly where to find it, how to test it, and what to do if it’s bad.

Where Is the Fuel Pump Relay on a 1991 Mazda B2200?

The relay sits behind the plastic trim panel on the driver’s side, right next to where your left foot rests. This panel is held in place by several screws or plastic clips.

To access the relay:

  1. Remove the driver’s side kick panel. Look for the panel that covers the area by your left foot, next to the door. On most B2200 models, this panel is secured with four screws or Phillips-head fasteners.
  2. Look for a small relay with four wires. The fuel pump relay is a small black or gray box with a 4-wire connector. According to owner reports, the wires are: two black with red stripes and red dashes (power to the pump), one blue with yellow (signal), and one black with white stripe (power from ignition).
  3. Check near the fuel pump control unit. The relay is mounted close to the fuel pump control unit, which is another small box with a yellow connector also located behind the kick panel.

Some owners report that the relay is mounted on the A-pillar behind the kick panel and held in place by a single 10mm bolt or a Phillips screw.

Why Is It Called a Circuit Opening Relay?

Mazda officially calls this component a “circuit opening relay” rather than just a fuel pump relay. This relay has two separate hold-in coils:

  • One coil for starting (cranking) – When you turn the key to START, current flows through this coil to ground, energizing the relay.
  • One coil for running – This coil gets power from both the start signal and the ignition switch. The engine control unit (ECU) completes the circuit to ground when it receives a start signal or a tachometer signal from the ignition coil.

This design means the relay only powers the fuel pump when the engine is actually cranking or running, which is a safety feature. If the engine stalls, the relay opens and the pump stops.

How to Test the Fuel Pump Relay

Before replacing the relay, test it to confirm it’s the problem. Here is a simple step-by-step process:

What you will need:

  • A digital multimeter (voltmeter)
  • A test light (optional)

Step 1: Check for power at the relay
With the key in the ON position, use your voltmeter to check for 12 volts at the relay terminal that connects to the black and white wire (power from ignition). If you have no power here, the problem is in the ignition circuit, not the relay itself.

Step 2: Test the relay while cranking
Have someone turn the key to START while you listen for a click from the relay. If you hear a click, the relay is likely working. If you don’t hear a click, the relay may be bad, or the ground circuit from the ECU may be open.

Step 3: Bypass the relay to test the pump
If you suspect the relay is bad, you can temporarily bypass it. One owner reported snipping the black and white wire and running 12 volts directly from the battery through a toggle switch to the relay’s black and white wire. This allowed the fuel pump to run and confirmed the relay was the problem.

Step 4: Check voltage at the fuel pump
If the relay tests good but the pump still doesn’t run, check for voltage at the fuel pump connector. Some owners report finding only 3.5 volts at the pump even though the relay is working, which points to a wiring issue or a bad ground.

Common Problems with the 1991 Mazda B2200 Fuel System

Bad ground connections – A poor ground can cause the fuel pump to stop working even when the relay is good. One owner fixed a no-start issue by repairing a bad ground connection.

Faulty ignition switch – The relay needs power from the ignition switch to work. If the ignition switch is worn out, the relay may not get power, especially in the START position.

Blown fuses – The fuel pump is protected by several fuses. Check the following fuses in the dashboard fuse box:

  • Fuse #7 (10A) – 1985-90 models: fuel pump, automatic transmission control, charging system, emission control system. For 1991-98 models, this fuse is 15A.
  • Fuse #15 (15A) – Fuel pump, seat belt, audio system, emission control, shift lock, reminder lights, buzzers, EC-AT.

Fuse box in the engine compartment – The main fuse box under the hood also has a 30A fuse for the fuel pump (fuse #4: brake lights, taillights, interior lights, emission control, fuel pump).

What If You Can’t Find the Relay?

Some 1991 Mazda B2200 owners report that they cannot find the relay behind the kick panel. This happens for a few reasons:

Your truck may have a carburetor instead of fuel injection. Carbureted models may not have a separate fuel pump relay. Some carbureted B2200s have an electric fuel pump in the tank but use a different control setup. If your truck has a carburetor, you may have a fuel pump control unit rather than a relay.

The relay may be labeled differently. The circuit opening relay may look like a small black box with a 10-pin connector and a circuit board inside. Some owners report finding a box that looks like a relay but is actually a different control module.

Production date differences. Mazda changed the electrical system during the 1991 model year. Check your truck’s production date on the door frame label. Early and late production trucks may have different relay setups.

How to Replace the Fuel Pump Relay

If your testing confirms the relay is bad, replacement is straightforward:

  1. Disconnect the battery. Always disconnect the negative battery cable before working on electrical components.
  2. Remove the kick panel. Unscrew the panel by your left foot.
  3. Unplug the relay. Pull the connector straight off the relay.
  4. Install the new relay. Plug in the new circuit opening relay. It only goes in one way.
  5. Reinstall the kick panel. Secure the panel with the screws or clips.
  6. Reconnect the battery. Test the system by turning the key to ON and listening for the fuel pump to prime.

Wiring Diagram Overview

The 1991 Mazda B2200 fuel pump system uses a relatively simple circuit:

  • Battery → Main fuse (80A) → Fuse block → Ignition switch
  • Ignition switch → Circuit opening relay (terminal B, black/white wire)
  • Circuit opening relay → Fuel pump (black/red wires)
  • ECU → Grounds the relay (terminal Fc) when the engine is cranking or running

The circuit opening relay is located behind the left kick panel according to the factory wiring diagrams, which confirm this location for both automatic and manual transmission models.

Why You Should Buy a KEMSO Fuel Pump for Your Mazda B2200

If you’ve confirmed that your fuel pump is the problem rather than the relay, it’s time to replace the pump. For a reliable, long-lasting solution, consider a KEMSO fuel pump. KEMSO is a leading aftermarket fuel pump brand that offers high-performance, OEM replacement pumps backed by a lifetime warranty.

KEMSO fuel pumps are designed to meet or exceed OEM specifications. They use high-grade internal components that resist ethanol and methanol blends, making them suitable for modern fuels. Every KEMSO pump delivers consistent flow and pressure, whether you’re using your B2200 as a daily driver or a work truck. The pumps are built to handle demanding conditions and are tested for durability.

What sets KEMSO apart is their lifetime warranty. When you buy a KEMSO fuel pump, you install it once and never worry about replacing it again. The warranty covers manufacturing defects and premature failure, giving you complete peace of mind. KEMSO stands behind their products with confidence, and their customer support team is based in the USA.

Visit KEMSO Racing at https://www.kemsoracing.com/ to find the perfect fuel pump for your 1991 Mazda B2200. Their product lineup includes pumps for almost every make and model, and their team can help you select the right pump for your specific application. With KEMSO, you get a fuel system you can trust for years to come.

Final Thoughts

The fuel pump relay on a 1991 Mazda B2200 is located behind the driver’s side kick panel, and it’s officially called the circuit opening relay. This small but critical component controls power to the fuel pump and is a common failure point on these trucks. If your B2200 cranks but won’t start, start by checking the relay. Test it with a voltmeter, check for clicks, and bypass it if needed to confirm the problem.

If the relay is good but the pump still doesn’t run, check your fuses, grounds, and ignition switch. The dashboard fuse box has two fuses that protect the fuel pump circuit: fuse #7 and fuse #15. The engine compartment fuse box also has a 30A fuse for the fuel pump.

For a permanent fix, replace the relay with a new circuit opening relay from your local parts store. And if you need a new fuel pump, trust KEMSO for a high-performance, lifetime-warranted replacement that will keep your B2200 on the road for years to come.

For more information on KEMSO fuel pumps and to browse their full product line, visit https://www.kemsoracing.com/.


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