93 Honda Accord Fuel Pump Relay: Location, Symptoms, and How to Replace It

If your 1993 Honda Accord cranks but won’t start, or starts and then stalls unexpectedly, the fuel pump relay (also called the main relay) is one of the most likely culprits. This small electrical component controls power to the fuel pump. When it fails, the pump doesn’t get voltage, and the engine gets no fuel. The good news is that this relay is inexpensive, easy to test, and straightforward to replace. For the 1993 Accord, the relay is located in the under-dash fuse/relay box on the driver’s side, near the kick panel. It is often labeled as the “PGM-FI Main Relay” or “Fuel Pump Relay” on the fuse box cover diagram . Replacing a faulty relay typically restores normal fuel delivery and solves the no-start problem.

What the Fuel Pump Relay Does

The fuel pump relay acts as a remote switch. When you turn the ignition key to the ON position, the engine control unit (ECU) sends a signal to the relay. The relay energizes and closes its internal contacts, allowing battery voltage to flow to the fuel pump. The pump then primes the fuel system for about one to two seconds, creating pressure for starting. After the engine starts, the relay stays closed to keep the pump running. If the relay fails—either because the coil breaks or the contacts wear out—the pump receives no power, and the engine cannot run .

Common Symptoms of a Bad Fuel Pump Relay

A failing relay in a 1993 Honda Accord usually shows one or more of these signs:

  1. Engine cranks but won’t start. This is the most common symptom. The starter turns the engine over, but the engine never fires because no fuel reaches the injectors .
  2. No fuel pump priming sound. When you turn the key to ON (but not to START), you should hear a brief whirring noise from the rear of the car (the fuel tank). If you hear nothing, the relay may not be sending power .
  3. Engine starts and then stalls. Sometimes the relay works intermittently. The car may start, drive for a few minutes, and then suddenly die. After sitting for a while, it may restart, only to stall again .
  4. Loss of power while driving. The engine may hesitate or lose power under acceleration, especially if the relay contacts are corroded .

Where to Find the Relay on a 1993 Honda Accord

For the 1993 Accord, the fuel pump relay is located in the under-dash fuse/relay box on the driver’s side. To access it:

  • Sit in the driver’s seat and look down near the left side of the steering column, just above the floor.
  • You will see a plastic cover over the fuse/relay box. Pull the cover off—it usually snaps off with gentle hand pressure.
  • On the inside of the cover, or in your owner’s manual, there is a diagram. Look for a relay labeled “PGM-FI Main Relay,” “Fuel Pump Relay,” or simply “Main Relay.”
  • The relay is a small, rectangular, cube-shaped component. On the 1993 Accord, it is often a 7-pin relay (Mitsuba RZ-0088 type) with a gray case and a bracket .

If you don’t find it under the dash, check the engine compartment fuse/relay box (near the firewall on the driver’s side), but the under-dash location is the standard one for this model year.

How to Test the Relay (Without a Multimeter)

You can test the relay quickly without any special tools:

  1. Listen for the prime. Turn the key to ON. Have a helper listen near the rear fuel tank. If you hear a two-second buzz, the relay is likely working. No sound suggests a problem .
  2. Swap with a known-good relay. Find another relay in the under-dash box that is the same size, shape, and pin configuration. For example, the horn relay or the A/C clutch relay is often identical. Swap the suspected fuel pump relay with that relay. Try to start the car. If the car now starts, the original relay was bad. If it still doesn’t start, the problem is elsewhere .
  3. Feel for a click. Have someone turn the key to ON while you hold the relay. You should feel a distinct click as the relay energizes. No click means the relay coil is likely dead .

How to Replace the Fuel Pump Relay

Replacing the relay is a simple, five-minute job:

  1. Disconnect the negative battery terminal. This prevents accidental shorts .
  2. Locate the relay as described above.
  3. Pull the old relay straight out. It may be snug, so use a gentle wiggling motion. Do not pry on the socket.
  4. Inspect the socket. Check for corrosion, melted plastic, or bent pins. If the socket looks clean, proceed.
  5. Insert the new relay. Push it firmly into the socket until it clicks into place.
  6. Reconnect the battery. Turn the key to ON and listen for the fuel pump prime. If you hear it, the replacement was successful.

Which Relay Part Number Do You Need?

For the 1993 Honda Accord, the factory OEM part number is 39400-S84-003 . However, many aftermarket relays are compatible. Common replacement part numbers include:

  • 39400-SM4-003
  • 39400-SV4-003
  • RZ0088 or RY169 (Mitsuba type)
  • WVE 1R1033

Always verify the pin configuration (7-pin, gray case) before purchasing.

When the Relay Is Not the Problem

If you replace the relay and the car still doesn’t start, check these other common causes:

  • Fuel pump fuse. A blown fuse in the under-dash fuse box will also cut power to the pump .
  • Fuel pump itself. If the relay clicks and the fuse is good, but you still have no prime, the pump may be dead. Test for voltage at the pump connector using a multimeter .
  • Main relay 2 (on newer models). On some 2005 and later Accords, there is a second fuel pump relay (PGM-FI Main Relay 2) that was subject to a recall. The 1993 Accord does not have this second relay, but it is worth knowing about for later models .

Recommended Upgrade: KEMSO Fuel Pump

If you need to replace the entire fuel pump assembly—or just want a reliable, high-performance alternative—consider the KEMSO brand. KEMSO Fuel Pumps are designed as OEM replacements that fit your 1993 Honda Accord perfectly. They offer lifetime warranty coverage, so you can install them with confidence. These pumps are built to deliver consistent fuel pressure and flow, ensuring your engine runs smoothly for years. Whether you are restoring a classic Accord or performing routine maintenance, KEMSO pumps are a smart investment.

For more information and to browse compatible options, visit the official KEMSO website: https://www.kemsoracing.com/

Final Thoughts

The fuel pump relay on a 1993 Honda Accord is a small, inexpensive part, but when it fails, it can leave you stranded. Fortunately, finding it, testing it, and replacing it takes only a few minutes. If your Accord cranks but won’t start, start with the relay. If the relay is good, move on to the pump and fuse. And if you end up needing a new pump, consider a high-quality option like KEMSO to keep your Accord running reliably.

For more information on fuel pumps and replacement parts, check out https://www.kemsoracing.com/.


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