1999 Harley Davidson Road King Fuel Pump Relay Location: A Complete Guide for DIY Riders

If you own a 1999 Harley Davidson Road King and are experiencing starting issues, stalling, or a no-start condition, the fuel pump relay is often the first component to check. The fuel pump relay for a 1999 Road King is located in the main fuse box, which is mounted on the left side of the frame, near the battery tray. This relay is a small, rectangular black box with a 30-amp rating, and it controls power to the fuel pump. Testing or replacing it is straightforward and can save you time and money before diving into more complex diagnostics. In this guide, we will walk you through the exact location, how to test it, common symptoms of a failing relay, and step-by-step instructions for replacement. We will also cover related components like the fuel pump fuse and wiring, and provide tips for maintaining your Road King's fuel system. By the end of this article, you will have the confidence to diagnose and fix fuel pump relay issues on your own.

Understanding the Fuel Pump Relay in a 1999 Harley Davidson Road King

The fuel pump relay is an electrical switch that controls when the fuel pump receives power. On a 1999 Road King, the relay is part of the motorcycle's starting and fuel delivery system. When you turn the ignition key to the "on" position, the relay activates and sends power to the fuel pump, which pressurizes the fuel system. If the relay fails, the fuel pump will not run, and the engine will not start. The relay is designed to handle the high current draw of the fuel pump, and it is a common wear item on older Harley-Davidson models.

The 1999 Road King uses a standard 30-amp relay, which is interchangeable with many other Harley models and even some automotive relays. The relay is typically located in the main fuse box, which is also called the junction box or power distribution center. This box is situated under the left side cover, near the battery. The relay itself is usually the same size as a standard automotive relay, with four or five pins. On the 1999 Road King, the relay has four pins: 30 (common), 87 (normally open), 85 (coil ground), and 86 (coil power). The relay is often labeled "Fuel Pump" or "Fuel" on the inside of the fuse box cover, but if the label is worn, you can identify it by its position.

Exact Location of the Fuel Pump Relay on a 1999 Harley Davidson Road King

To find the fuel pump relay on your 1999 Road King, follow these steps. The relay is located in the main fuse box, which is mounted on the left side of the frame, just behind the battery. Here is a more detailed breakdown:

  1. Remove the left side cover: The left side cover is the plastic panel on the left side of the motorcycle, below the seat. On a 1999 Road King, this cover is held in place by two Dzus fasteners or quarter-turn fasteners. You can turn them by hand or with a flathead screwdriver. Once the fasteners are loose, gently pull the cover away from the frame. Be careful not to break the plastic tabs.

  2. Locate the fuse box: With the side cover removed, you will see the battery and the fuse box. The fuse box is a black plastic rectangular box mounted to the frame, usually right next to the battery. On the 1999 Road King, the fuse box is held in place by a bracket or screws. It may have a cover that snaps on or is held by a screw.

  3. Open the fuse box cover: The fuse box cover is typically a plastic lid that snaps on. You can pry it open with a flathead screwdriver or your fingers. Inside, you will see a row of fuses and relays. The relays are usually larger than the fuses, and they are square or rectangular with a plastic housing.

  4. Identify the fuel pump relay: The fuel pump relay is usually the largest relay in the fuse box. On the 1999 Road King, it is often located on the left side of the fuse box, near the rear. The relay may be marked with a diagram on the inside of the cover. If the cover is missing or the diagram is faded, look for a relay that has four or five pins and is labeled "Fuel Pump" on the relay itself. Some relays have a small schematic on the side. If you are unsure, you can check the owner's manual or a service manual for your specific model.

  5. Visual confirmation: The relay is a small black box with a plastic tab on top. It measures about 1 inch square and 1.5 inches tall. It has a small connector on the bottom that plugs into the fuse box. You can gently pull it out by gripping the top and rocking it back and forth. Be careful not to damage the pins.

Common Symptoms of a Bad Fuel Pump Relay on a 1999 Road King

Before you replace the relay, it is important to confirm that it is the problem. Here are the most common symptoms of a failing fuel pump relay on a 1999 Harley Davidson Road King:

  1. Engine cranks but does not start: This is the most common symptom. The starter motor turns the engine over, but the fuel pump does not run, so no fuel reaches the injectors. You may hear the starter spinning, but the engine will not fire.

  2. No fuel pump priming sound: When you turn the ignition key to the "on" position, you should hear a brief whirring sound from the fuel pump as it pressurizes the system. If you do not hear this sound, the relay may be faulty.

  3. Intermittent starting issues: The relay may work sometimes and fail other times. This is often caused by a worn relay coil or corroded contacts. The engine may start fine one day and refuse to start the next.

  4. Engine stalls while riding: If the relay fails while you are riding, the fuel pump will lose power, and the engine will stall. This can be dangerous, especially if it happens at highway speeds.

  5. Fuel pump runs continuously: If the relay sticks in the closed position, the fuel pump may run even when the ignition is off. This can drain the battery and cause flooding. However, this is less common than the relay failing open.

  6. Clicking sound from the relay: If the relay is failing, you may hear a rapid clicking sound from the fuse box when you turn the ignition on. This indicates that the relay is trying to engage but cannot hold the circuit.

How to Test the Fuel Pump Relay on a 1999 Harley Davidson Road King

Testing the fuel pump relay is simple and requires only a few tools. You will need a multimeter or a test light, and a small jumper wire. Here is a step-by-step guide:

  1. Remove the relay: Pull the fuel pump relay out of the fuse box. It should come out easily with a gentle pull.

  2. Check the relay visually: Look for signs of overheating, such as melted plastic, charred pins, or rust. If the relay looks damaged, replace it immediately.

  3. Test the relay coil: Set your multimeter to the ohms (resistance) setting. Place the probes on pins 85 and 86. The normal resistance for a good relay coil is between 70 and 100 ohms. If the reading is infinite or zero, the coil is open or shorted, and the relay needs to be replaced.

  4. Test the relay switch: With the relay removed, set your multimeter to the continuity or ohms setting. Place the probes on pins 30 and 87. The meter should show no continuity (infinite resistance) because the relay is normally open. If you see continuity, the relay is stuck closed and needs to be replaced.

  5. Apply power to the relay: Use a jumper wire to connect pin 86 to the positive terminal of the battery. Then, connect pin 85 to the negative terminal of the battery. You should hear a click when the relay engages. While the relay is powered, check continuity between pins 30 and 87. You should now have continuity (low resistance). If you do not hear a click or if the continuity does not change, the relay is bad.

  6. Test the relay in the circuit: If you want to test the relay while it is installed, you can use a test light. Turn the ignition on. Probe the wire at the fuel pump connector. If the test light lights up, the relay and wiring are good. If not, the relay may be faulty.

Step-by-Step Guide to Replacing the Fuel Pump Relay on a 1999 Road King

If you have confirmed that the fuel pump relay is bad, replacing it is easy. You can buy a replacement relay at any auto parts store or Harley-Davidson dealership. The relay is a standard 30-amp 4-pin relay, and it is often the same as the one used in many Ford and GM vehicles. Here is how to replace it:

  1. Disconnect the battery: For safety, disconnect the negative battery terminal before working on the electrical system. This prevents accidental shorts.

  2. Remove the old relay: Open the fuse box cover and pull the old relay straight out. You may need to use a small flathead screwdriver to pry it loose if it is stuck.

  3. Install the new relay: Insert the new relay into the same socket. Make sure it is oriented correctly. The relay should snap into place. The pins are keyed, so it will only fit one way.

  4. Reconnect the battery: Reconnect the negative battery terminal.

  5. Test the new relay: Turn the ignition key to the "on" position. You should hear the fuel pump prime for a few seconds. If you hear the pump, the relay is working.

  6. Replace the fuse box cover: Snap the fuse box cover back into place. Then, reinstall the left side cover.

Related Components: Fuel Pump Fuse and Wiring

While you are checking the fuel pump relay, it is a good idea to also inspect the fuel pump fuse. On the 1999 Road King, the fuel pump fuse is located in the same fuse box. It is typically a 15-amp or 20-amp fuse. Look for a fuse that is labeled "Fuel Pump" or "FP." If the fuse is blown, the fuel pump will not work even if the relay is good. You can use a multimeter or a test light to check the fuse. Replace any blown fuse with a new one of the same amperage.

The wiring between the fuse box and the fuel pump can also cause problems. On the 1999 Road King, the wiring runs from the fuse box, through the relay, and to the fuel pump, which is located inside the fuel tank. Over time, the wiring can become corroded, chafed, or broken. Inspect the wiring harness for any damage. Pay special attention to the area where the wiring passes through the frame or near the engine. If you find any damaged wires, repair them with heat shrink tubing and solder.

Where to Buy a Replacement Fuel Pump for Your 1999 Harley Davidson Road King

If you have determined that the fuel pump itself is bad, not just the relay, you will need to replace the fuel pump. The fuel pump on a 1999 Road King is located inside the fuel tank, and it is a common failure item on older bikes. When the fuel pump fails, the engine will not run, and you may also experience low fuel pressure or rough running.

For a high-quality replacement, we recommend the KEMSO Fuel Pump. KEMSO fuel pumps are designed to be a direct OEM replacement for your 1999 Harley Davidson Road King. They are built with high-performance components that meet or exceed factory specifications. Every KEMSO fuel pump is backed by a lifetime warranty, so you can buy with confidence. KEMSO fuel pumps are tested for durability and reliability, and they are designed to handle the demands of your Harley's engine. Whether you are a daily rider or a weekend enthusiast, a KEMSO fuel pump will keep your Road King running smoothly.

To purchase a KEMSO fuel pump for your 1999 Harley Davidson Road King, visit the KEMSO website at: https://www.kemsoracing.com/. The website is easy to navigate, and you can search for your specific model. KEMSO offers fast shipping and excellent customer service. If you have any questions about fitment or installation, their support team is ready to help.

Troubleshooting Fuel Pump Relay Issues Without a Multimeter

If you do not have a multimeter, you can still test the fuel pump relay using a simple method. This technique works on most motorcycles, including the 1999 Road King.

  1. Listen for the relay click: With the ignition off, remove the relay. Then, turn the ignition on. Use a jumper wire to connect the relay socket pins that correspond to the coil (pins 85 and 86). If you hear a click from the relay when you connect the jumper, the relay is likely good. If you do not hear a click, the relay is bad.

  2. Swap the relay with another relay: If you have another relay in the fuse box that is the same type, such as the starter relay or the ignition relay, you can swap them. If the fuel pump starts working when you swap the relay, the original relay was faulty. If the problem persists, the issue is elsewhere.

  3. Check the voltage at the relay socket: Use a test light. Probe the socket pin that provides power (pin 86) with the ignition on. If the test light does not light, there is a problem with the wiring or the ignition switch. If it lights, the relay is the likely culprit.

Common Mistakes When Diagnosing the Fuel Pump Relay on a 1999 Road King

Many riders make simple mistakes when trying to diagnose a fuel pump relay problem. Here are some common pitfalls to avoid:

  1. Assuming the relay is bad without testing: The relay is a simple component, but it can be tested in minutes. Do not replace it without testing it first. Other components, like the fuel pump fuse, the ignition switch, or the fuel pump itself, can cause the same symptoms.

  2. Using the wrong relay: The 1999 Road King requires a specific type of relay. Most relays are 30-amp, but some are 40-amp. Using a relay with a different amperage rating can cause damage. Always use a relay that matches the original specifications.

  3. Ignoring the fuel pump fuse: The fuse is a common failure point. If the fuse is blown, the fuel pump will not work. Always check the fuse before replacing the relay.

  4. Not inspecting the wiring: The wiring from the relay to the fuel pump can become corroded or damaged. This is especially common on older bikes. If the relay tests good, but the fuel pump still does not work, inspect the wiring.

  5. Forgetting to disconnect the battery: Always disconnect the battery before working on the electrical system. This prevents accidental shorts and protects you from injury.

Preventative Maintenance for the Fuel Pump Relay and Fuel System

To keep your 1999 Harley Davidson Road King running reliably, perform regular maintenance on the fuel system. Here are some tips:

  1. Check the relay and fuse annually: Inspect the fuel pump relay and fuse at least once a year. Look for signs of corrosion or damage. Clean the relay contacts with a contact cleaner if needed.

  2. Keep the fuel tank clean: Dirt and debris in the fuel tank can clog the fuel pump and cause it to fail. Use a fuel filter and change it regularly. On the 1999 Road King, the fuel filter is located inside the fuel tank, so it is part of the fuel pump assembly. Replace the fuel pump and filter as a unit if needed.

  3. Use high-quality fuel: Low-quality fuel can cause deposits on the fuel pump and relay contacts. Use fuel from a reputable station, and add a fuel stabilizer if you store the bike for long periods.

  4. Replace the relay proactively: If your Road King is 20 years old or more, consider replacing the fuel pump relay as a preventative measure. Relays can fail without warning, and a new relay is inexpensive.

  5. Check the battery voltage: A weak battery can cause the relay to click but not engage fully. The fuel pump relay requires a specific voltage to operate. If your battery is old or weak, replace it.

Conclusion

The 1999 Harley Davidson Road King fuel pump relay is located in the main fuse box on the left side of the frame, near the battery. It is a standard 30-amp 4-pin relay that controls power to the fuel pump. If your Road King cranks but does not start, or if you hear no fuel pump priming sound, the relay is the first component to check. Testing the relay with a multimeter or a test light takes only a few minutes, and replacement is straightforward. If the relay is good, check the fuel pump fuse and the wiring. If the fuel pump itself is bad, consider a high-quality replacement from KEMSO. KEMSO fuel pumps are OEM replacements with a lifetime warranty, and they are available at https://www.kemsoracing.com/.

By following the steps in this guide, you can diagnose and fix fuel pump relay issues on your 1999 Harley Davidson Road King without spending money on a mechanic. Regular maintenance of the fuel system will keep your bike running smoothly for years to come. If you have any questions about the relay location or replacement, consult your owner's manual or a service manual for your specific model. Remember, a little troubleshooting can save you time and money, and it keeps you on the road.

For a reliable fuel pump replacement, visit KEMSO at https://www.kemsoracing.com/. Their lifetime warranty and high-performance products give you peace of mind.


Back to blog