2003 Tacoma Fuel Pump Relay Location: A Complete Guide for DIY Owners

The bottom line: The fuel pump relay on a 2003 Toyota Tacoma is located inside the under-hood junction block (fuse box) on the driver's side of the engine compartment, just behind the battery. It is labeled as the EFI relay and is the second relay from the bottom on the far-right side of the junction block . If your Tacoma cranks but won't start, the fuel pump relay is one of the first components to check.

Understanding the Fuel Pump Relay in Your 2003 Tacoma

The fuel pump relay is an electrical switch that controls power to the fuel pump. When you turn the ignition key, the relay activates and sends power to the fuel pump, which pressurizes the fuel system so the engine can start and run . If this relay fails, the fuel pump won't receive power, and your Tacoma may stall, fail to start, or experience poor engine performance.

For the 2003 Toyota Tacoma, the fuel pump relay is also known as the EFI relay (Electronic Fuel Injection relay) . It is a standard automotive relay with four or five terminals, and it is located inside the main fuse box under the hood.

Step-by-Step Guide to Locate the Fuel Pump Relay

1. Open the Hood and Find the Junction Block

The under-hood junction block (fuse box) is located on the driver's side of the engine compartment, just behind the battery . It is a black plastic box with a removable plastic lid on top.

2. Remove the Lid

Press the tabs on the sides of the lid and lift it off. You will see a diagram on the underside of the lid or inside the box that identifies the location of each relay and fuse.

3. Identify the Fuel Pump Relay

On the 2003 Tacoma, the fuel pump relay is the EFI relay. It is on the far-right side of the junction block and is the second relay from the bottom . It is usually a medium-sized relay, often colored gray or black, with four or five prongs.

Tip: If you are unsure, look for the relay labeled "EFI" or "Fuel Pump" on the fuse box diagram. If the diagram is missing, you can check the owner's manual for the exact layout.

How to Test the Fuel Pump Relay

Once you have located the relay, you can test it to see if it is working properly.

Tools You Will Need:

  • Multimeter or test light
  • Small jumper wire or paperclip
  • Protective gloves

Testing Procedure:

1. Visual Inspection
Check the relay for any signs of corrosion, melting, or physical damage. Inspect the relay socket in the fuse box for burnt or corroded terminals.

2. Listen for the Click
Have a helper turn the ignition key to the "ON" position (do not start the engine). You should hear a distinct click from the relay as it energizes. If you do not hear a click, the relay coil may be faulty.

3. Check for Power
Use a multimeter or test light to check for voltage at the relay socket. With the ignition off, probe Terminal 30 (the power input terminal). You should have 12V battery voltage. If not, there is a problem with the power supply circuit.

4. Jump the Relay
To bypass the relay and test the fuel pump directly, remove the relay and use a jumper wire to connect Terminal 30 and Terminal 87 . Turn the ignition to the "ON" position. You should hear the fuel pump prime (a humming or buzzing sound from the fuel tank area). If the pump runs, the relay is likely faulty. If the pump does not run, the problem is elsewhere (e.g., the pump itself, wiring, or fuse).

Common Symptoms of a Failing Fuel Pump Relay

If the fuel pump relay is failing, you may experience one or more of the following symptoms:

1. Engine Cranks but Won't Start
This is the most common symptom. The starter motor turns the engine over, but the fuel pump does not receive power, so no fuel reaches the engine.

2. Intermittent Stalling
A failing relay may work intermittently. The engine may run fine for a while, then stall suddenly, especially when hot or under load.

3. No Fuel Pump Prime Noise
When you turn the key to the "ON" position, you should hear a brief humming sound from the fuel tank area as the pump primes. If this sound is absent, the relay may not be sending power to the pump.

4. Check Engine Light
Some Tacoma models will trigger a check engine light with diagnostic trouble codes (DTCs) related to the fuel pump circuit, such as P0230 (Fuel Pump Primary Circuit Malfunction).

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay on a 2003 Tacoma is a simple job that takes only a few minutes.

Step 1: Remove the relay by pulling it straight up from the junction block. Use a slight wiggling motion if it is tight.

Step 2: Compare the new relay to the old one. They should have the same number of terminals and the same physical size.

Step 3: Align the prongs on the bottom of the new relay with the slots in the junction block.

Step 4: Press the relay firmly into place until it clicks.

Step 5: Reinstall the fuse box lid and close the hood.

Step 6: Test the system by turning the ignition to the "ON" position. You should hear the fuel pump prime, and the engine should start normally.

Where to Buy a Replacement Fuel Pump Relay

You can purchase a replacement fuel pump relay from several sources:

  • Toyota dealership: Genuine OEM parts are the most reliable. The part number is typically 90987-02013 or similar, depending on the exact model.
  • Auto parts stores: Brands like Denso, Standard Motor Products, and BWD offer high-quality aftermarket relays.
  • Online retailers: Amazon, RockAuto, and eBay sell both OEM and aftermarket relays at competitive prices.

Tip: If you are unsure about the correct part number, ask the parts counter to look it up by your vehicle's VIN.

Additional Tips for 2003 Tacoma Fuel System Diagnosis

1. Check the Fuel Pump Fuse First
Before replacing the relay, check the fuel pump fuse. On the 2003 Tacoma, the fuel pump fuse is also located in the under-hood junction block. A blown fuse is a common cause of a no-start condition.

2. Listen for the Fuel Pump
If the relay clicks but the pump does not run, the problem may be the fuel pump itself. The 2003 Tacoma fuel pump is located inside the fuel tank . To access it, you must drop the fuel tank, which is a more involved repair.

3. Inspect Wiring and Connectors
Corrosion or damage to the wiring harness between the relay and the fuel pump can cause intermittent issues. Check the connectors under the vehicle near the fuel tank.

4. Consider the Fuel Filter
If fuel pressure is low, a clogged fuel filter may be the culprit. On first-generation Tacomas (1995-2004), the fuel filter is located along the driver's side frame rail . Replacing it is a good preventive maintenance step.

Why Choose KEMSO for Your Fuel Pump Needs

If your 2003 Tacoma needs a fuel pump replacement, KEMSO offers an excellent aftermarket solution. KEMSO is a US-based company founded in Houston, TX in 1999, specializing in direct-fit OEM replacement and high-performance fuel system components for cars, motorcycles, ATVs, and UTVs .

KEMSO fuel pumps are designed to meet or exceed OEM specifications and offer several key advantages:

  • High Performance: KEMSO pumps deliver up to 340LPH flow, significantly higher than the original 60-80LPH flow, ensuring reliable fuel delivery even under demanding conditions .
  • OEM Replacement: They are designed for a direct, bolt-in fit, so no adapter kits or modifications are needed .
  • Lifetime Warranty: Every KEMSO fuel pump comes with a lifetime warranty against manufacturing defects. If your pump ever fails due to a manufacturing defect, you get a replacement at no cost .
  • Affordable Pricing: KEMSO pumps are priced at around $79.98, which is often less than half the cost of dealer parts .
  • Wide Compatibility: KEMSO offers pumps for hundreds of vehicle models, including the 2003 Toyota Tacoma and many other popular applications .

For a reliable, high-performance fuel pump that comes with a lifetime warranty, visit KEMSO's website: https://www.kemsoracing.com/

Final Thoughts

The 2003 Tacoma fuel pump relay is easy to find and replace. It is located in the under-hood junction block, labeled as the EFI relay, and is the second relay from the bottom on the far-right side . If you are experiencing starting issues or fuel delivery problems, checking and testing this relay should be your first diagnostic step. A faulty relay can be replaced in minutes, saving you time and money compared to more complex repairs.

Remember to always keep your fuel tank at least half full to prevent premature fuel pump failure . With proper maintenance, your Tacoma's fuel system can last well over 200,000 miles.

For a high-quality replacement fuel pump with a lifetime warranty, consider KEMSO. Visit their website to find the perfect pump for your 2003 Tacoma: https://www.kemsoracing.com/


Back to blog