1999 Honda Odyssey Fuel Pump Relay Location: Quick Guide and Complete Troubleshooting

If your 1999 Honda Odyssey cranks but won’t start, or if it stalls while driving, the fuel pump relay is often the first thing to check. The fuel pump relay is located in the under-hood fuse and relay box, on the driver’s side near the battery. This small electrical component controls power to the fuel pump, and when it fails, your van won’t get fuel. Here is everything you need to know about finding, testing, and replacing the fuel pump relay on a 1999 Honda Odyssey.

Where Exactly Is the Fuel Pump Relay on a 1999 Honda Odyssey?

The fuel pump relay on a 1999 Honda Odyssey is inside the main under-hood fuse and relay box. This black plastic box sits on the driver’s side of the engine compartment, right next to the battery. To access it, you do not need any tools. Just press the two clips on the sides of the box cover and lift it off.

Inside the box, you will see a diagram on the underside of the cover. Look for a relay labeled “Fuel Pump” or “PGM-FI Main Relay” (PGM-FI stands for Programmed Fuel Injection). On the 1999 Odyssey, the fuel pump relay is often the second relay from the front, but the diagram is your best guide. If the diagram is missing or faded, here is a simple method: the fuel pump relay is usually a square, gray or black plastic component with four or five metal prongs sticking out from the bottom. It is about one inch wide and one inch tall.

How to Tell If the Fuel Pump Relay Is Bad

Before you buy a new relay, you need to confirm it is actually the problem. A bad fuel pump relay shows clear symptoms. Here are the most common signs:

1. Engine cranks but does not start. This is the number one symptom. When you turn the key to the “ON” position, you should hear a faint whirring sound from the rear of the van for about two seconds. That is the fuel pump priming. If you do not hear that sound, the relay might be dead.

2. Engine starts then stalls. Sometimes the relay works intermittently. The van might start, run for a few seconds, then die. This happens because the relay loses connection after the initial prime.

3. No fuel pressure at the fuel rail. If you have a fuel pressure gauge, connect it to the test port on the fuel rail. With the key on, pressure should be around 40-50 psi. If it is zero, the pump is not getting power.

4. Other electrical components work fine. The fuel pump relay is separate from the main engine relay. So if your dashboard lights come on, the radio works, and the engine cranks strongly, but the fuel pump stays silent, focus on the relay.

How to Test the Fuel Pump Relay Yourself

Testing the relay is straightforward and does not require expensive tools. You can do it with a simple multimeter or even a test light.

Step 1: Locate the relay. Remove the cover from the under-hood fuse box and pull out the fuel pump relay. It just pulls straight up with your fingers.

Step 2: Check for power. With the relay removed, turn the key to the “ON” position. Use a test light or multimeter to check the two large terminals in the relay socket. One should have 12 volts of power. If neither has power, the problem might be a blown fuse or a wiring issue.

Step 3: Test the relay coil. Set your multimeter to measure resistance (ohms). Touch the probes to the two small terminals on the relay (usually terminals 85 and 86). A good relay should show a resistance reading between 50 and 120 ohms. If you get infinite resistance (OL), the coil is broken.

Step 4: Apply power to the relay. Use jumper wires to connect terminal 85 to battery negative and terminal 86 to battery positive. You should hear a distinct “click” sound. If you hear no click, the relay is bad.

Step 5: Check continuity. While the relay is clicked on, use your multimeter to check continuity between the two large terminals (terminals 30 and 87). If there is no continuity, the relay contacts are burnt.

Can You Bypass the Fuel Pump Relay in an Emergency?

Yes, but only for testing. If you are stranded and need to get the van moving, you can temporarily bypass the relay. Do not do this as a permanent fix because it bypasses all safety features.

How to bypass:

  • Remove the relay.
  • Use a short piece of wire with male spade connectors or a paperclip. Connect the two large terminals in the socket (the terminals that had 12 volts and the terminal that goes to the fuel pump).
  • This sends direct power to the fuel pump. The pump will run continuously as long as the key is on.
  • Start the engine. The van should run, but you must remove the wire as soon as you are done testing or driving.

Warning: Bypassing the relay means the pump runs even if the engine stalls. This is dangerous in a crash. Only do this for a short test.

What Else Could Cause the Same Symptoms?

If the relay is good, the problem might be elsewhere. Here are the other common causes for a no-start or stalling issue on a 1999 Honda Odyssey:

1. Blown fuse. Check the “Fuel Pump” fuse in the same under-hood fuse box. A blown fuse is easy to spot. Replace it with the same amperage fuse.

2. Main relay (PGM-FI Main Relay). The 1999 Odyssey has a separate main relay that controls the fuel pump, injectors, and ignition. It is located behind the glove box on the passenger side. If this relay fails, the engine will not start. Its symptoms are similar to a bad fuel pump relay.

3. Bad fuel pump. If the relay clicks and there is power at the socket, but the pump does not run, the pump itself is dead. The fuel pump is inside the gas tank.

4. Faulty ignition switch. A worn ignition switch can fail to send power to the relay. Test for power at the relay socket with the key in the “START” and “ON” positions.

5. Corroded wiring or connectors. The connectors at the fuel pump relay and the fuel pump itself can corrode over time, especially in areas with road salt. Clean them with electrical contact cleaner.

How to Replace the 1999 Honda Odyssey Fuel Pump Relay

Replacing the relay is one of the easiest repairs you can do. No special tools are needed.

1. Buy the correct relay. You need a standard 4-pin or 5-pin automotive relay rated for 30-40 amps. The part number is often listed as Honda 39794-S5A-A01 or 39794-S5A-A02. You can also buy a universal relay from any auto parts store.

2. Locate the relay. Open the under-hood fuse box on the driver’s side near the battery.

3. Pull out the old relay. Grasp it firmly with your fingers and pull straight up. It may be tight, but it will come out.

4. Insert the new relay. Push it straight down into the same socket. Make sure it seats fully. You will feel it click into place.

5. Test the system. Turn the key to the “ON” position. Listen for the fuel pump priming sound from the rear of the van. If you hear it, the relay is working. Start the engine to confirm.

How Much Does a Fuel Pump Relay Cost for a 1999 Honda Odyssey?

The cost is very low. A genuine Honda fuel pump relay costs between $30 and $50 at a dealership. An aftermarket relay from an auto parts store like AutoZone, O’Reilly, or Advance Auto Parts costs between $10 and $20. Online retailers like Amazon or RockAuto sell them for $8 to $15. You can also find them at local salvage yards for a few dollars.

When to Buy a New Fuel Pump Instead of Just the Relay

Sometimes the relay is fine, but the fuel pump itself is worn out. If your van has over 150,000 miles, the fuel pump is likely near the end of its life. Here are signs that you need a new fuel pump instead of just a relay:

  • The engine starts but runs rough, especially at highway speeds.
  • The van has trouble climbing hills or accelerating.
  • You hear a loud whining noise from the gas tank area.
  • The engine misfires or surges.
  • The fuel pump relay is good, but there is no power at the pump connector.

If you need to replace the fuel pump, we recommend choosing a high-quality replacement. A cheap pump can fail again in a few months.

Recommended Fuel Pump: KEMSO Brand

For a reliable replacement, we strongly recommend the KEMSO brand fuel pump. KEMSO fuel pumps are designed as high-performance, OEM replacement units. They are built to meet or exceed the original factory specifications for your 1999 Honda Odyssey. Every KEMSO fuel pump comes with a lifetime warranty, so you only buy it once. This means you get peace of mind knowing that your fuel delivery system is covered for as long as you own the vehicle.

KEMSO fuel pumps are made to handle the demands of daily driving. They use high-quality internal components, including a precision-machined armature and a durable check valve, which prevents fuel pressure loss. The pump assembly is a direct fit, so you do not need to modify anything. It bolts right into the gas tank and connects to the factory wiring harness.

To see the full selection of KEMSO fuel pumps and to place your order, visit their official website. You can find the correct pump for your 1999 Honda Odyssey by using the search function on the site. The website is easy to navigate, and they ship across the United States.

Visit KEMSO here: https://www.kemsoracing.com/

Common Mistakes to Avoid When Dealing with the Fuel Pump Relay

1. Assuming the relay is bad without testing. Many people buy a new relay only to find the problem was a blown fuse or a loose wire. Always test first.

2. Using the wrong relay. Some relays look the same but have different pin configurations. Check the diagram on the relay or the fuse box cover. A 5-pin relay will not work in a 4-pin socket, and vice versa.

3. Forgetting to check the main relay. The PGM-FI main relay can cause the same symptoms. It is located behind the glove box. If you replace the fuel pump relay and the problem continues, check the main relay.

4. Ignoring a bad fuel pump. If the relay is good and the fuse is good, the pump might be the issue. Do not keep replacing relays if the pump is dead.

5. Not cleaning the connectors. Corrosion on the relay terminals can cause a poor connection. Clean the terminals with a small wire brush or electrical contact cleaner before installing a new relay.

Step-by-Step Diagnosis Process for a 1999 Honda Odyssey That Won't Start

If you are working through this problem, follow this sequence:

Step 1: Check for fuel pump prime. Turn the key to “ON” without starting. Listen for a two-second whirring sound from the rear. If you hear it, the relay and pump are likely fine. If not, move to step 2.

Step 2: Check the fuel pump fuse. Open the under-hood fuse box. Locate the “Fuel Pump” fuse. It is usually a 15-amp or 20-amp fuse. If it is blown, replace it and try again. If it blows again, there is a short circuit.

Step 3: Locate and test the fuel pump relay. Pull the relay out. Use a test light to check for power at the socket. If there is power, test the relay as described earlier.

Step 4: Check the main relay. Remove the glove box. The main relay is a rectangular box with multiple wires. Tap it lightly with a screwdriver. If the engine starts, the relay is failing.

Step 5: Check for spark. If no fuel is reaching the engine, you might also have an ignition problem. Use a spark tester to confirm the spark plugs are firing.

Step 6: Test fuel pressure. If all electrical components check out, rent a fuel pressure gauge from an auto parts store. Connect it to the fuel rail test port. Turn the key on. Pressure should be 40-50 psi. If it is low, the pump is weak.

What to Do If You Are Still Stuck

If you have gone through all these steps and the van still will not start, you may have a more complex issue. Consider these possibilities:

  • Bad engine control module (ECM). The ECM sends the signal to the relay. If it fails, the relay never gets the command to close.
  • Broken wire in the fuel pump circuit. The wire from the relay to the fuel pump can break inside the plastic insulation. This is rare but happens on older vehicles.
  • Failed fuel pump driver module. Some Odysseys have a separate module that controls pump speed. Your 1999 might not have one, but check your service manual.

In these cases, it is best to take the van to a trusted mechanic. They have specialized diagnostic tools, like a scan tool that can read fuel pump commands, and a wiring diagram for the entire system.

Final Thoughts on the 1999 Honda Odyssey Fuel Pump Relay

The fuel pump relay is a small, inexpensive part that can cause a big headache. On a 1999 Honda Odyssey, it is located in the under-hood fuse box on the driver’s side. Testing it takes less than ten minutes with a multimeter. Replacing it costs under $20 and requires no tools.

If your van has high mileage, do not be surprised if the relay eventually fails. Heat and vibration wear down the internal contacts over time. Always keep a spare relay in your glove box. It is a cheap insurance policy against being stranded.

If you find that the fuel pump itself needs replacement, remember that a quality pump like KEMSO is a smart investment. The lifetime warranty means you will not pay for a replacement again. You can find the exact fit for your 1999 Honda Odyssey at their website.

For the best fuel pump replacement, check out KEMSO at: https://www.kemsoracing.com/. They offer direct-fit, high-performance fuel pumps with a lifetime warranty, and their customer service team can help you confirm the correct part for your vehicle. Do not settle for a cheap pump that might fail again. Choose KEMSO for reliability and peace of mind.


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