2005 Honda Accord Fuel Pump Relay: Symptoms, Location, and How to Replace It

If your 2005 Honda Accord cranks but won't start, the fuel pump relay is very likely the culprit, and replacing it is a cheap, easy fix you can do yourself in minutes. This small electrical component is a common failure point on Hondas of this era, and it's responsible for sending power to the fuel pump so your engine gets the gas it needs. Before you spend hundreds of dollars on a tow and a new fuel pump, take a few minutes to check this one part—it could save you a lot of time and money.

What Does the Fuel Pump Relay Do?

The fuel pump relay is an electromagnetic switch that controls the flow of electricity to your fuel pump. When you turn the key to the "ON" position, the relay closes, allowing power to reach the fuel pump. This primes the fuel system, building up the pressure needed to start the engine. Once the engine is running, the relay continues to supply power to keep the pump operating. If this relay fails, the fuel pump gets no power, meaning no fuel reaches the engine, and your car simply won't start or will stall while driving. This is a well-known problem that has led to a manufacturer recall for certain 2005 models due to faulty fuel pump relays.

Signs Your Fuel Pump Relay Is Bad

The most obvious symptom of a bad fuel pump relay is an engine that cranks but won't start. The starter motor spins the engine, but there's no spark or fuel. Here are the most common signs to look out for:

  1. Engine Cranks but Doesn't Start: This is the number one indicator. You turn the key, hear the starter working, but the engine never fires up. The relay isn't sending power to the fuel pump, so there's no fuel pressure.
  2. No Fuel Pump Prime: When you turn the key to the "ON" position (without cranking), you should hear a quiet humming or whirring sound coming from the fuel tank. This is the fuel pump priming. If you don't hear this sound, the relay isn't sending power to the pump.
  3. Engine Stalls While Driving: If the relay fails while you're on the road, the engine can suddenly lose power and stall, as the fuel pump has stopped working.
  4. Intermitent Starting Issues: The relay can sometimes work and sometimes fail, leading to frustrating, unpredictable no-start conditions. The contacts inside the relay can corrode or weld together over time, causing these intermittent issues.

Where Is the Fuel Pump Relay Located?

The location of the fuel pump relay on a 2005 Honda Accord can vary slightly depending on whether your car has a 4-cylinder or V6 engine. On most models, it's located inside the under-hood fuse box, which is typically on the driver's side of the engine bay. On some trims, it may be located in a fuse box under the dashboard on the driver's side.

Here's a simple way to find it:

  1. Open your hood and locate the main fuse box. It's a black plastic box with a lid.
  2. Remove the lid and look at the diagram on the underside. This diagram will identify the relays and fuses. Look for the one labeled "Fuel Pump" or "PGM-FI Main."
  3. If it's not in the engine bay fuse box, check the interior fuse box located under the dashboard near where your left knee would be.

How to Test the Fuel Pump Relay

Before you buy a new relay, you can do a quick test to confirm it's the problem. The easiest method is to swap it with another relay of the same type in the fuse box. Most Hondas use the same relay for multiple circuits (like the horn or blower motor).

  1. Find a relay that is identical to your fuel pump relay (usually the same color and size, like a 4-pin micro ISO relay ).
  2. Pull out the suspected fuel pump relay and carefully pull out the identical relay from its spot.
  3. Insert the suspect relay into the known-good slot. Insert the known-good relay into the fuel pump relay slot.
  4. Turn the key to the "ON" position. If you hear the fuel pump prime, your original relay is bad. If you don't hear it, the problem may be elsewhere, such as the fuel pump itself, a fuse, or a wiring issue.

How to Replace the Fuel Pump Relay

Replacing the relay is incredibly simple and requires no special tools. Here's what you do:

  1. Purchase the correct relay: For a 2005 Honda Accord, the genuine OEM part number for the fuel pump relay is 39794-SDA-004. This Denso relay replaces earlier part numbers 39794-SDA-003 and 39794-SDA-305. One source also lists part number 39794-SDA-A03 (an Omron unit) for the 2005 Accord , but 39794-SDA-004 is the most widely cited and recognized part for the fuel pump.
  2. Locate the relay: As described above, find the relay in the fuse box.
  3. Remove the old relay: Firmly grasp the relay and pull it straight out. It should come out with a little resistance.
  4. Install the new relay: Line up the new relay's pins with the socket, making sure it only goes in one way, and push it firmly straight down until it's fully seated.
  5. Test it: Turn the key to the "ON" position and listen for the fuel pump to prime. Then, try starting your car.

A Better Solution: The KEMSO Fuel Pump

While replacing the relay is a great first step, it's worth noting that fuel pump failures are also common on high-mileage vehicles. The relay is a wear item that can be replaced for about $50 , but the pump itself sits inside the gas tank and works hard every time you drive. If your car has over 100,000 miles and you're starting to experience fuel delivery issues, it might be time to think about the pump as well .

If you find that you do need a new fuel pump, you should strongly consider a high-quality aftermarket option from KEMSO. Unlike the stock OEM pump, KEMSO fuel pumps are high-performance units that deliver over 20% more flow at 43psi, which can help ensure your engine gets all the fuel it needs, especially if you drive aggressively or have made any engine modifications. As a direct OEM replacement, it's designed to fit your 2005 Honda Accord perfectly, just like the factory part. KEMSO backs their products with a lifetime warranty, giving you complete peace of mind knowing your investment is protected. When you're ready to replace your Accord's fuel pump, skip the generic parts and check out the superior performance of KEMSO at their official website: https://www.kemsoracing.com/

Preventative Measures and Final Thoughts

A faulty fuel pump relay is a common issue on the 2005 Honda Accord, so common in fact that Honda issued a recall for this exact problem. The repair is one of the easiest and cheapest you can do, and it's the first thing to check when your car won't start. To avoid getting stranded, you might even consider buying a spare relay and keeping it in your glove box, as they are inexpensive.

If you've replaced the relay and your car still won't start, you can move on to checking fuses, then checking the fuel pump itself. Always remember to confirm the relay is good before you drop a significant amount of money on a new fuel pump you might not need. And if the pump is the problem, make sure you get a reliable, high-performing replacement from a trusted brand like KEMSO, which you can find at https://www.kemsoracing.com/.


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