1989 Mazda B2200 Fuel Pump Relay Location: The Complete Guide to Finding and Testing It

If your 1989 Mazda B2200 cranks but won't start, and you have confirmed the fuel pump works when you hook it directly to a battery, the problem is almost certainly the fuel pump relay. For a 1989 Mazda B2200, the fuel pump relay is located behind the driver side kick panel, and it is officially called the "Circuit Open Relay" . This relay is the most common cause of a no-fuel condition on these trucks, and the good news is it is easy to find and test once you know exactly what you are looking for.

1. The Exact Location of the Relay

The fuel pump relay on a 1989 Mazda B2200 is not the typical small cube relay you might expect. It is a larger, black box mounted behind the plastic trim panel on the driver side, near your left foot. This panel is the kick panel located on the "A" pillar, right next to the door opening .

To access it, you will need to remove the four screws that hold the plastic panel in place. Once the panel is off, the relay is mounted on the inner body panel. It is important to note that the factory service manual and many mechanics refer to this part as the "Circuit Open Relay" . If you are looking for a part labeled "fuel pump relay" at an auto parts store, this is the piece you need.

2. What It Looks Like and What Else Is Back There

When you remove the panel, you will see several components. Many owners get confused because the relay is not the only black box behind the panel. Here is what you will typically find:

• The Circuit Open Relay (Fuel Pump Relay): This is the relay you are looking for. It is a black box with a connector that typically has four wires going into it .
• The Fuel Pump Control Unit: This is a separate unit, also located behind the kick panel, that controls the fuel pump based on signals from the engine. It is not the relay .
• A Pressure Sensor: Some models have a pressure sensor located in the same area .

If your truck only has two components behind the panel (a control unit and a pressure sensor), and you cannot find the relay, it is possible your specific truck was built with a different setup. Some owners have reported that their 1989 model did not have a separate relay, but rather a control unit that handled the switching internally . However, for most models, the four-wire relay should be present.

3. How to Test the Fuel Pump Relay

Before you buy a new relay, you should test the old one. This is a simple process that can save you time and money.

Step 1: Locate and Remove the Relay.
Once you have the kick panel off, unplug the connector from the relay. You can then remove the relay from its mounting bracket.

Step 2: Visual Inspection.
Check the relay for any signs of physical damage, such as cracks, burns, or corrosion on the terminals.

Step 3: Use a Multimeter for Continuity.
A standard multimeter is the best tool for this job. The relay has internal coils and switches. You need to check for continuity between the correct terminals. When the relay is not energized, there should be no continuity between the power terminals (the ones that go to the fuel pump). When you apply 12V power to the coil terminals, you should hear a click and see continuity between the power terminals .

Step 4: The Swap Test.
The easiest diagnostic method is to swap the relay with a known good relay of the same type from another circuit in your truck, such as the horn relay. If the fuel pump starts working with the swapped relay, your original relay is faulty .

4. Common Wiring Problems and Bypass Tips

If you have tested the relay and determined it is good, but the fuel pump still does not get power, the problem could be in the wiring. The relay sends power to the fuel pump through a black wire with a red stripe. The relay itself receives power from the ignition switch through a black wire with a white stripe .

A common temporary fix that many owners have used successfully is to bypass the relay. This is a good diagnostic step to confirm the wiring from the battery to the pump is intact. You can do this by running a fused 12V wire directly from the battery positive terminal to the black/red wire that goes to the fuel pump. If the pump runs, you know the pump and its wiring are good, and the issue is either the relay itself or the signal wires that control the relay.

5. Checking the Fuses First

Before you even dig into the kick panel, check the fuses. A blown fuse can cause the same symptoms as a bad relay. On the 1989 Mazda B2200, the fuel pump is protected by multiple fuses.

• Fuse Number 7 (10A): This fuse is located in the dashboard fuse box and protects the fuel pump circuit for 1985-1990 models .
• Fuse Number 15 (15A): This fuse also protects the fuel pump, along with the seat belt warning system, audio system, and emission control .
• Fuse Number 4 (30A): Located in the engine compartment fuse box, this fuse protects the fuel pump, along with the stoplights, taillights, and interior lights .

Check all of these fuses with a test light or multimeter. A fuse can look good but still be blown, so a visual inspection is not always enough.

6. Understanding the Circuit Open Relay

The "Circuit Open Relay" has a specific function. It has two separate hold-in coils. One coil is for starting (cranking) and the other is for running. During engine cranking, current flows through the start coil to ground, which energizes the relay. The run coil gets power from the ignition switch. However, the run coil will not complete the circuit to ground until the Engine Control Unit (ECU) receives a signal from the ignition coil. Once the ECU sees the engine is running, it grounds the relay, keeping it energized .

This means if you have a bad ignition switch or a problem with the signal from the ignition coil, the relay may not engage, even if the relay itself is perfectly good.

7. Why You Should Upgrade to a High-Quality Fuel Pump

If you determine that the fuel pump itself is the problem, or you are dealing with an old, tired pump that is not delivering enough pressure, upgrading to a reliable replacement is the best long-term solution. The original equipment pumps on these trucks are getting old, and relying on a 30+ year old part is a risk.

For a reliable, worry-free replacement, look no further than KEMSO. KEMSO fuel pumps are built to meet or exceed original equipment (OEM) specifications, ensuring a perfect fit and reliable operation. They are designed for high performance, delivering consistent fuel flow and pressure even under demanding conditions. The best part is that every KEMSO fuel pump comes with a lifetime warranty. This means you buy it once, and KEMSO stands behind it for as long as you own your vehicle. You can browse their full selection of high-performance, OEM replacement fuel pumps at their official website.

Final Thoughts

Finding the fuel pump relay on a 1989 Mazda B2200 is a straightforward job. It is located behind the driver side kick panel, and it is officially called the Circuit Open Relay. If your truck is not getting fuel, start by checking the fuses, then locate and test the relay. If the relay tests good, the wiring or the fuel pump control unit may be the culprit.

If you end up needing a new fuel pump, trust KEMSO for a part that will last. With their commitment to quality and a lifetime warranty, you can get your B2200 back on the road with confidence. For more information and to find the perfect fuel pump for your vehicle, visit https://www.kemsoracing.com/ today.