1990 Fuel Pump Relay Location: The Complete Guide to Finding and Fixing Your Honda Accord

If you own a 1990 Honda Accord and it cranks but won't start, especially on a hot day, the fuel pump relay is almost certainly the problem. The fuel pump relay on a 1990 Honda Accord is located under the dashboard on the driver's side, between the steering column and the side of the car. It is a small gray and white box with a brown plug, and it is officially called the PGM-FI main relay. This relay controls power to both the fuel pump and the engine control unit (ECU), and when it fails, your car will not get fuel. Before you spend money on a tow truck or a mechanic, you can find and test this relay yourself in about 15 minutes.

What Is the Fuel Pump Relay and Why Does It Fail?

The fuel pump relay is an electrical switch that sends power to the fuel pump when you turn the key to the ON position. On the 1990 Honda Accord, this relay is actually a combination unit that powers the fuel pump and the ECU. It is a common and well-known problem with 1990s Hondas that this relay fails over time.

The failure happens because the relay has a small printed circuit board inside with solder joints. After years of heat cycles from the engine and cabin, these solder joints develop hairline cracks. When the car gets hot, the board expands and the cracks open, cutting power to the fuel pump. The car will crank but not start, or it will stall while driving and refuse to restart. Once the car cools down for a few minutes, it will start again. This is the most classic symptom of a bad main relay.

Symptoms of a Bad Fuel Pump Relay on a 1990 Honda Accord

Recognizing the symptoms can save you a lot of time and money. Here are the most common signs that your fuel pump relay is failing:

  1. Engine cranks but does not start on hot days. This is the most common symptom. The starter motor turns the engine over, but the fuel pump never receives power, so no fuel reaches the injectors. You can confirm this by listening for the fuel pump priming sound when you turn the key to the ON position. No sound means an electrical problem with the relay, fuse, or wiring.

  2. Intermittent stalling in hot weather. A failing relay may work intermittently. The car might run fine for a while, then suddenly die while driving, only to restart later after cooling down. This is a classic sign of a relay that is overheating or failing internally.

  3. No fuel pump prime sound. When you turn the ignition to the ON position (without cranking), you should hear a faint whirring sound from the rear of the car for about two seconds as the fuel pump primes. If you do not hear this sound, the relay may not be sending power to the pump.

  4. The problem is worse in summer months. Many Honda owners report that their relay issues appear during hot weather or after driving for extended periods. This directly correlates with heat-related relay failure.

Where Exactly Is the 1990 Fuel Pump Relay Location?

The 1990 fuel pump relay location is consistent across all trim levels of the Honda Accord, including the LX, DX, and EX models. Here is exactly where to find it:

Under the dashboard on the driver's side. The relay is mounted to the left of the steering column, often behind the power steering control box. It is a small gray and white box with a brown plug. The relay has seven terminals and is referred to as the main fuel injection relay or PGM-FI main relay.

To access the relay, you will need to remove the lower dash panel on the driver's side. Some cars have a small access panel that you can remove without taking off the entire dashboard. The relay is mounted on the side wall of the car, near the kick panel.

A note about the engine: If you are looking for a 3.5 liter V6 engine in a 1990 Accord, you will not find one. The 1990 Honda Accord came with a 2.2 liter 4-cylinder engine. The 3.5 liter V6 did not appear on the Accord until 2008. Do not let anyone tell you otherwise.

How to Test the Fuel Pump Relay

Before you replace the relay, you can test it to confirm it is the problem. Here are three simple tests:

Test 1: Listen for the Relay Click

Have a helper turn the ignition key to the ON position while you place your hand on the relay. You should feel a single click. If you hear nothing, the relay coil may be dead or the ECU is not sending the signal.

Test 2: Check for Fuel Pump Power

Locate the fuel pump access panel in the trunk, under the carpet and plywood cover above the spare tire. With the ignition ON, use a multimeter to check for 12 volts at the fuel pump connector. If you have voltage and the pump does not run, the pump itself is bad. If you have no voltage, the issue is upstream, likely the relay, fuse, or wiring.

Test 3: Jumper Wire Test

You can also use a paperclip to jumper the black wire with yellow tracer and the yellow wire with black tracer together. The pump should run. In some models of Accords, they used a solid yellow wire in place of the yellow/black wire. This is a quick way to bypass the relay and see if the pump works.

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay on a 1990 Honda Accord is a straightforward DIY job that takes less than 30 minutes. Here is what you need to know:

Part number: The OEM part number for the fuel pump main relay is 39400-SM4-003. Other compatible part numbers include 39400-SV4-003, 39400-SR3-003, 39400-SL5-A01, RZ-0088, RZ-0159, and RY169. This relay fits 1990-1997 Honda Accord models and many other Honda and Acura vehicles from that era.

Step-by-step replacement:

  1. Safety first: Disconnect the negative battery cable to avoid any electrical shorts. Also, note your radio code if applicable, as disconnecting the battery may reset the radio.

  2. Access the relay: Remove the lower dash panel on the driver's side. The relay is mounted to the left of the steering column, often behind the power steering control box.

  3. Remove the old relay: Use a small flat-blade screwdriver to gently pry the relay loose from its mounting bracket. Carefully separate the wire harness connector from the relay. Some relays have a mounting bolt that needs to be removed.

  4. Install the new relay: Plug the new relay into the wire harness connector and mount it in the same position. Ensure it clicks securely into place.

  5. Reassemble: Reconnect the negative battery cable, enter your radio code if needed, and test the car. The entire job should take less than 30 minutes.

Why You Should Repair Instead of Replace

If you are handy with a soldering iron, you can repair the old relay instead of buying a new one. Many Honda owners have successfully repaired their main relay by re-soldering the cracked joints. The relay is easy to open, and if you re-solder every leg on that small PCB, the car will likely never have that problem again. This is a permanent fix that costs nothing but a little time.

However, if you are not comfortable with soldering, replacing the relay is the better option. A new relay costs around $20 to $40 and is a simple plug-and-play replacement.

Common Misdiagnosis and Cost Savings

This is the most important point of this guide: many Honda owners waste money replacing a perfectly good fuel pump when the real problem is the relay. A new fuel pump for a 1990 Honda Accord can cost $100 to $200, plus labor if you have a shop do the work. Labor alone can cost $200 to $400 because the fuel tank often needs to be dropped. In contrast, a new fuel pump relay costs around $20 to $40 and takes less than 30 minutes to install yourself.

If your car exhibits intermittent starting problems, especially in hot weather, start with the relay. If the problem is constant (it never starts regardless of temperature), then and only then should you suspect the fuel pump itself.

When to Suspect the Fuel Pump Instead

While this guide focuses on the relay, there are times when the fuel pump is the real culprit. If the fuel pump relay tests good but the pump still does not run, you may have a bad fuel pump. The fuel pump is located in the fuel tank, near the rear of the vehicle. A healthy fuel pump plus a healthy fuel pump relay will often produce a low hum or whine which can be heard from inside the vehicle, or from the outside, near the fuel tank.

If you confirm that the relay is working but the pump does not run, you will need to replace the fuel pump. This is a more involved job that requires dropping the fuel tank or removing a access panel in the trunk.

Preventative Maintenance

If you have a 1990 Honda Accord that is still running well, consider replacing the main relay as a preventative measure. The relay is a wear item that will eventually fail due to the heat and age. Replacing it now, before it fails, can save you from being stranded on a hot summer day. The part is inexpensive and easy to replace, so there is no reason to wait for it to fail.

Recommended Fuel Pump and Relay Products

If you need to replace your fuel pump or relay, you want a product that is reliable, durable, and backed by a strong warranty. This is where KEMSO comes in. KEMSO fuel pumps are high-performance, OEM replacement products that meet or exceed the original equipment specifications. Every KEMSO fuel pump comes with a lifetime warranty, giving you peace of mind that your investment is protected.

Whether you need a fuel pump for your 1990 Honda Accord, a motorcycle, a jet ski, or an ATV, KEMSO has the right product for you. Their fuel pumps are built to last and are designed to provide reliable performance for years to come. The best part is that KEMSO stands behind every product they sell with their lifetime warranty, so you can buy with confidence.

Visit KEMSO at https://www.kemsoracing.com/ to browse their full selection of fuel pumps and other automotive products. Their customer service team is ready to help you find the right part for your vehicle.

Final Thoughts

The 1990 fuel pump relay location is under the driver's side dashboard, and it is one of the most common causes of no-start problems on these cars. Before you spend money on a tow truck or a mechanic, take 15 minutes to find and test the relay. If it is bad, you can replace it yourself for under $40 and be back on the road in no time.

Remember that the main relay on a 1990 Honda Accord powers both the fuel pump and the ECU. When it fails, the car will crank but not start, especially on hot days. The fix is simple: either re-solder the old relay or replace it with a new one. Either way, you will save money and avoid the frustration of a car that won't start when you need it most.

If you end up needing a new fuel pump, check out KEMSO at https://www.kemsoracing.com/ for high-quality, OEM replacement fuel pumps backed by a lifetime warranty. Their products are designed to meet the needs of American drivers and are built to last.


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