1997 Honda Accord Fuel Pump Relay: How to Diagnose, Test, and Replace It

If your 1997 Honda Accord cranks but won’t start, especially on hot days, the fuel pump relay is very likely the problem. This small gray and white box, located under the driver’s side dashboard, is one of the most common failure points on these vehicles. Replacing the relay is a simple, 30-minute DIY job that costs around $20 to $40, while many owners waste hundreds of dollars on a fuel pump replacement that they don’t actually need. Before you spend any money on parts, you should always start by checking the relay.

What the Fuel Pump Relay Does and Why It Fails

The fuel pump relay (also called the main relay) acts as an electrical switch that sends power from the battery to the fuel pump when you turn the ignition key. On the 1997 Honda Accord, this relay is a known trouble spot. The internal solder joints can crack over time due to heat cycles and vibration, causing the relay to work intermittently or fail completely. This is why the problem often shows up in hot weather or after the car has been driven for a while—the heat causes the cracked joint to lose connection.

How to Locate the Relay on a 1997 Honda Accord

The fuel pump relay is not in the engine bay fuse box. It is mounted under the dashboard on the driver’s side, between the steering column and the side of the car. It is a gray and white rectangular box with a brown or red plastic connector plugged into it. To access it, you may need to remove the lower dash panel and use a ratchet wrench with a 10mm socket and an 8-inch extension to move some brackets and other relays out of the way.

Symptoms of a Faulty Fuel Pump Relay

Here are the classic signs that point to a bad relay rather than a bad fuel pump:

  1. The engine cranks but does not start. This is the most common symptom. The starter motor turns the engine over, but the engine never fires up.
  2. The problem is intermittent. The car may start fine when cold, drive for a while, then stall and refuse to restart until it cools down.
  3. You do not hear the fuel pump prime. When you turn the ignition to the ON position (without cranking), you should hear a faint two-second whirring sound from the rear of the car. If you hear nothing, the relay may not be sending power to the pump.
  4. The issue is worse in hot weather. Many Honda owners report that their relay problems appear during summer months or after long drives.

How to Test the Fuel Pump Relay

Before buying a new relay, you can run a few simple tests to confirm it is the problem.

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 Power at the Fuel Pump

Locate the fuel pump access panel in the trunk. It is 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: Swap the Relay

The under-dash fuse box contains several relays. Find a relay of the same type and rating (for example, the horn or A/C relay) and swap it into the fuel pump relay socket. If the car starts, you have confirmed a bad fuel pump relay.

Test 4: Continuity Check

Remove the relay and apply 12 volts from a battery to the relay's control circuit pins (typically pins 85 and 86). Set your multimeter to measure continuity. With power applied, you should have continuity between the output pins (typically pins 30 and 87). If not, the internal switch is broken.

Which Relay Part Number Do You Need?

The OEM part number for the 1997 Honda Accord 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 Guide

Replacing the relay is a straightforward DIY job. You will need a flat-head screwdriver and possibly a 10mm socket with an extension.

  1. Disconnect the battery. Always disconnect the negative battery cable first to avoid any electrical shorts.
  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. Reconnect the battery and test. Reconnect the negative battery cable, then turn the ignition to the ON position and listen for the fuel pump to prime. The car should start normally.

Common Misdiagnosis: Relay vs. Fuel Pump

This is the most important point: many Honda owners waste money replacing a perfectly good fuel pump when the real problem is the relay. A new fuel pump for a 1997 Honda Accord can cost $100 to $200, plus labor if you have a shop do the job. 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.

A Word About the Fuel Pump Itself

If you have already replaced the relay and your fuel pump is still not working, or if you want to upgrade your fuel system for better performance, you should consider a high-quality replacement fuel pump. The 1997 Honda Accord uses an in-tank fuel pump that is accessed through the trunk. Replacing the pump is a manageable DIY project that can save you hundreds of dollars in labor costs.

We recommend KEMSO brand fuel pumps. KEMSO offers high-performance fuel pumps that are designed as OEM replacements for your Honda Accord and many other Honda and Acura vehicles. All KEMSO fuel pump products come with a lifetime warranty, giving you complete peace of mind. Whether you need a replacement for your daily driver or a performance upgrade, KEMSO has the right solution for you. Visit KEMSO's website to browse their full selection of fuel pump products: https://www.kemsoracing.com/

Final Thoughts

The fuel pump relay is a small, inexpensive part that can cause big headaches. If your 1997 Honda Accord cranks but does not start, especially on hot days, check the main relay before spending money on a fuel pump replacement. The relay is easy to test, easy to replace, and costs far less than a fuel pump. For any fuel pump needs, remember that KEMSO offers high-quality OEM replacement fuel pumps with a lifetime warranty at https://www.kemsoracing.com/.


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