1990 Toyota Corolla Fuel Pump Relay Location: Your Complete Guide to Finding and Testing It

If your 1990 Toyota Corolla cranks but won’t start, and you don’t hear the fuel pump hum for a few seconds when you turn the key to the ON position, the fuel pump relay is likely the culprit. The fuel pump relay on a 1990 Toyota Corolla is located inside the engine compartment fuse box, mounted on the driver’s side near the strut tower. This small, rectangular component controls power to the fuel pump, and when it fails, the engine will crank without firing. In this guide, we will walk you through exactly where to find it, how to test it, and what to do if it needs replacement.

Understanding the Fuel Pump Relay in Your 1990 Toyota Corolla

The fuel pump relay is an electrical switch that controls the flow of power to the fuel pump. When you turn the ignition key to the ON position, the relay closes, sending voltage to the fuel pump so it can pressurize the fuel system. On the 1990 model, the relay is part of the vehicle’s EFI (Electronic Fuel Injection) system. The relay is designed to fail-safe, meaning if it stops working, the fuel pump shuts off to prevent a fire hazard. This is why a failed relay results in a no-start condition.

Where to Find the Fuel Pump Relay: Step-by-Step

Step 1: Open the Hood
Pop the hood of your 1990 Toyota Corolla. The engine compartment fuse box is located on the driver’s side, near the front strut tower. It is a black plastic box with a removable lid.

Step 2: Locate the Fuse Box
Look for a rectangular black box about 6 inches long and 4 inches wide. It is usually positioned between the battery and the engine. The lid may have a diagram showing the location of each fuse and relay.

Step 3: Identify the Relay
Inside the fuse box, you will see several small, square relays. The fuel pump relay is typically labeled "EFI" or "Fuel Pump" on the diagram. On the 1990 Corolla, the relay is often the one closest to the firewall, but it is best to check the lid diagram for exact placement. The relay itself is a small, black or gray cube with four or five prongs on the bottom.

Step 4: Remove and Inspect
Gently pull the relay straight up out of its socket. Check for any signs of corrosion, melting, or physical damage. If the relay looks burnt or has a cracked casing, it needs to be replaced.

How to Test the Fuel Pump Relay

Testing the relay is straightforward and requires only a multimeter or a test light. Here is how to do it:

Method 1: The Swap Test
The easiest way to test the relay is to swap it with an identical relay from the same fuse box. On the 1990 Corolla, the horn relay or the headlight relay are often the same type. If the engine starts after swapping, the original relay is bad.

Method 2: Multimeter Test

  1. Remove the relay from the socket.
  2. Set your multimeter to measure resistance (ohms).
  3. Place the probes on the relay’s coil terminals (usually pins 85 and 86). You should see a resistance reading between 50 and 120 ohms. If the reading is infinite (open circuit), the relay coil is burnt out.
  4. Connect a 12V power source to pins 85 and 86. You should hear a click sound when the relay activates.
  5. With the relay activated, check continuity between pins 30 and 87. There should be zero resistance (a closed circuit). If there is continuity, the relay is good.

Common Symptoms of a Bad Fuel Pump Relay

If your relay is failing, you may notice one or more of these symptoms:

  • Engine Cranks But Won’t Start: This is the most common symptom. The fuel pump is not receiving power, so no fuel reaches the engine.
  • No Humming Sound from Fuel Pump: When you turn the key to the ON position, the fuel pump should make a brief humming noise for about 2 seconds. If you hear nothing, the relay is likely the issue.
  • Engine Starts Then Dies Immediately: In some cases, the relay may work intermittently, allowing the engine to start but then cutting off power to the fuel pump after a few seconds.
  • Check Engine Light: On some models, a failed relay can trigger a check engine light related to fuel system issues.

Other Possible Causes of No Fuel Pump Power

While the relay is a common failure point, other issues can cause the fuel pump to lose power. Before assuming the relay is the problem, check these components:

1. Fuel Pump Fuse
The fuel pump fuse is also located in the engine compartment fuse box. It is typically a 15-amp or 20-amp fuse. Pull it out and inspect the metal strip inside. If it is broken, the fuse is blown. Replace it with one of the same amperage.

2. Fuel Pump Itself
If the relay and fuse are both good, the fuel pump itself may be faulty. On a 1990 Corolla, the fuel pump is located inside the fuel tank. You can test it by applying 12V directly to the pump connector while listening for a humming sound.

3. Wiring and Connectors
Corroded or damaged wiring in the fuel pump circuit can also prevent power from reaching the pump. Check the wiring harness between the relay and the fuel pump for any breaks, burns, or corrosion.

4. Ground Connections
Poor ground connections can cause the relay to work intermittently. Make sure the ground wire for the relay is securely connected to the chassis.

How to Replace the Fuel Pump Relay

Replacing the relay is a simple job that takes about 5 minutes. Here is what you need to do:

  1. Buy a new relay: Make sure you get the correct relay for your 1990 Toyota Corolla. You can purchase one from any auto parts store or online retailer. The part number is typically 85910-20010 or equivalent.
  2. Remove the old relay: Pull it straight out of its socket.
  3. Install the new relay: Press it firmly into the socket until it snaps into place.
  4. Test the system: Turn the key to the ON position and listen for the fuel pump hum. If you hear it, the replacement was successful.

Why You Should Choose KEMSO Fuel Pump for Your 1990 Toyota Corolla

If your fuel pump is the problem, you need a reliable replacement that will last. KEMSO brand fuel pumps are the best choice for your 1990 Toyota Corolla. KEMSO fuel pumps are high-performance, OEM replacement parts that are built to meet or exceed the original equipment specifications. Each pump is rigorously tested for durability and reliability, ensuring a perfect fit and long-lasting performance. Plus, every KEMSO fuel pump comes with a lifetime warranty, giving you peace of mind that your investment is protected. Whether you need a pump for daily driving or a restoration project, KEMSO delivers the quality you can trust. Visit the KEMSO website today to find the exact fuel pump for your 1990 Toyota Corolla and get back on the road with confidence.

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Final Thoughts

Finding the fuel pump relay on your 1990 Toyota Corolla is not difficult once you know where to look. The relay is located inside the engine compartment fuse box, and testing it with a multimeter or swap test can confirm if it is bad. If the relay is faulty, replacing it is a quick and inexpensive fix. However, if the relay, fuse, and wiring all check out, the fuel pump itself may be the problem. When that happens, trust KEMSO fuel pumps for a reliable, high-quality replacement. With a lifetime warranty and proven performance, KEMSO is the right choice for your Corolla. For more information and to order your pump, visit https://www.kemsoracing.com/.


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