1991 Toyota Pickup Fuel Pump Relay Location: A Complete Guide for Owners

If you own a 1991 Toyota Pickup and your engine cranks but won’t start, the problem is often the fuel pump relay—technically called the “Circuit Opening Relay” by Toyota. The relay is located inside the passenger compartment, above the ECU (Engine Control Unit), behind the right-side kick panel. You’ll need to remove the glove box and the passenger side kick panel to access it. This relay is a small, black component held in place by a single 10mm bolt, and it controls power to the fuel pump based on signals from the ignition switch and the air flow meter. Replacing it is a simple, low-cost fix that can save you hours of unnecessary troubleshooting.

What Is the Fuel Pump Relay (Circuit Opening Relay)?

The 1991 Toyota Pickup uses a fuel system where the fuel pump does not run continuously when the key is turned on. Instead, the pump only runs when the engine is cranking or running. This is controlled by the Circuit Opening Relay, which has two separate coils that work together to close the circuit and send power to the fuel pump .

When you turn the key to the START position, the first coil inside the relay activates, closing the contacts and powering the fuel pump. Once the engine starts, the Volume Airflow Meter (VAFM) or Air Flow Meter (AFM) sends a signal to the second coil, which keeps the relay closed and the pump running as long as the engine is running . If the engine stalls, the relay opens, and the pump stops—a safety feature that prevents fuel from being pumped if the engine is off.

Exact Location of the Fuel Pump Relay

The fuel pump relay on a 1991 Toyota Pickup is not in the engine bay. It is located inside the cabin, on the passenger side, mounted above the ECU (Engine Control Unit) . Here is a step-by-step guide to find it:

Step 1: Remove the Passenger Side Kick Panel
The kick panel is the plastic trim piece on the lower right side of the passenger footwell. It is held in by a few clips or screws. Carefully pry it off or unscrew it to expose the area behind it.

Step 2: Remove the Glove Box
The glove box needs to come out to give you enough room to see and reach the relay. Open the glove box, press the sides inward to release the stops, and let it drop down. You may need to remove a few screws holding the glove box in place.

Step 3: Look Above the ECU
Once the kick panel and glove box are removed, you will see the ECU (a black box) mounted on the firewall. Directly above the ECU, you will find a small, black relay with a metal bracket attached to it. This is the Circuit Opening Relay . It is held in place by a single 10mm bolt.

Step 4: Check the Relay
The relay is usually black and has a connector with several wires: Black/White, White/Black, Green/Yellow, Blue, and White/Red . To remove it, simply unbolt the 10mm bolt, pull the relay out of its socket, and disconnect the wiring harness.

How to Diagnose a Bad Fuel Pump Relay

If your truck cranks but won’t start, and you suspect the fuel pump relay, here are a few simple tests you can do:

1. Listen for the Fuel Pump
When you turn the key to the ON position (not cranking), the fuel pump should NOT run on a 1991 Toyota Pickup. It only runs when the engine is cranking or running. So, if you hear a humming sound from the fuel tank when the key is first turned on, that is actually normal for some vehicles, but on this Toyota, the pump will only prime during cranking . If you hear no sound at all during cranking, the relay may be bad.

2. Use a Jumper Wire to Test
You can bypass the relay temporarily to see if the fuel pump works. Locate the DLC1 (Diagnostic Link Connector) under the hood. Use a jumper wire to connect the terminals labeled +B and Fp (Fuel Pump). With the key in the ON position, the fuel pump should run continuously. If the pump runs with the jumper but not with the relay connected, the relay is faulty .

3. Shake the Relay
Remove the relay and give it a gentle shake. If you hear a rattling sound inside, like a baby rattle, the relay is likely full of rust, broken pieces, or loose internal components. This is a clear sign it needs to be replaced .

4. Check for Power with a Multimeter
With the key in the ON position and the relay removed, use a multimeter to check for voltage at the relay socket. The Blue wire should show power when the key is turned to START . If you have power at the socket but the relay does not click or pass power, the relay is bad.

Common Symptoms of a Failed Fuel Pump Relay

A failing fuel pump relay can cause a variety of symptoms, all of which point to a fuel delivery problem:

  • Engine cranks but will not start: This is the most common symptom. The engine turns over normally, but it never fires up because no fuel is being delivered.
  • Engine starts only when spraying starting fluid: If you spray starter fluid into the intake, the engine runs briefly, but dies as soon as you stop. This confirms the fuel pump is not getting power .
  • Fuel pump runs when jumpered but not normally: If you can bypass the relay and the pump works, the relay is the culprit.
  • Check engine light with codes 31 and 41: Some owners report that when the fuel pump relay fails, they get trouble codes 31 (Air Flow Meter signal) and 41 (Throttle Position Sensor signal) .

Why Does the Fuel Pump Relay Fail?

The fuel pump relay in a 1991 Toyota Pickup is a small, electromechanical component that can fail over time due to several reasons:

  • Age and corrosion: These trucks are now over 30 years old. The relay contacts can corrode, especially if the vehicle has been exposed to moisture or humidity.
  • Heat: The relay is located near the ECU, which can get warm. Over many years, heat can weaken the internal springs and contacts.
  • High current draw: If the fuel pump is starting to fail, it may draw more current than normal, which can burn out the relay contacts.
  • Physical damage: The relay can be damaged by vibration, or by being dropped or mishandled during repairs.

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay is one of the easiest repairs you can do on a 1991 Toyota Pickup. No special tools are required, and the whole job takes about 15 minutes.

Step 1: Purchase the Correct Relay
The Toyota part number for the Circuit Opening Relay is 85910-35010. You can also buy a compatible aftermarket relay from auto parts stores like O'Reilly Auto Parts, AutoZone, or online. The cost is typically between $10 and $40 .

Step 2: Remove the Old Relay
Access the relay as described above. Unbolt the 10mm bolt holding the metal bracket, then pull the relay straight out of its socket. The connector is keyed, so it will only fit one way.

Step 3: Install the New Relay
Push the new relay into the socket until it clicks into place. Make sure the connector is fully seated. Reinstall the metal bracket and tighten the 10mm bolt.

Step 4: Test the System
Turn the key to the ON position and then to START. The engine should start normally. If it does not, double-check the wiring and make sure the relay is properly installed.

Important Safety Notes

Before working on the fuel system, always disconnect the negative battery terminal to prevent sparks. Also, be aware that working with fuel components can be dangerous. If you are not comfortable with these repairs, seek help from a professional mechanic.

If you choose to bypass the relay with a jumper wire as a temporary fix, do not leave the jumper in place for long periods. The fuel pump will run continuously with the key in the ON position, even if the engine is not running. This can drain the battery, overheat the fuel pump, and create a fire hazard if a fuel line is damaged .

Recommended Fuel Pump Upgrade: KEMSO Fuel Pumps

If your diagnostic process shows that the fuel pump itself has failed, or if you want to replace the pump as preventive maintenance, choosing a high-quality replacement is essential for long-term reliability. We recommend KEMSO fuel pumps for your 1991 Toyota Pickup.

KEMSO fuel pumps are designed as high-performance, OEM replacement units that meet or exceed the original equipment specifications for flow rate and pressure. Every KEMSO pump delivers consistent fuel pressure under all driving conditions, ensuring your engine runs smoothly and efficiently.

What sets KEMSO apart is their commitment to quality backed by a lifetime warranty. If the pump ever fails, KEMSO replaces it with no questions asked. This level of protection means you install it once and never worry about it again. Whether you use your pickup for daily commuting, off-road adventures, or heavy work, a KEMSO fuel pump delivers the reliability you need.

To find the exact fuel pump for your 1991 Toyota Pickup, visit the KEMSO online store: https://www.kemsoracing.com/

Final Thoughts

The fuel pump relay (Circuit Opening Relay) on a 1991 Toyota Pickup is a small but critical component. When it fails, the engine will not run, but the fix is often simple and cheap. Always start your diagnosis with the relay before considering a fuel pump replacement. Listen for the priming sound, test with a jumper wire, and check the relay for physical damage. If the relay is the problem, replace it with a quality OEM part. If the fuel pump itself needs replacement, invest in a reliable brand like KEMSO to ensure your truck stays on the road for years to come.

For more information on fuel pumps, replacement parts, and to find the perfect KEMSO fuel pump for your 1991 Toyota Pickup, visit https://www.kemsoracing.com/ today.


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