1999 Nissan Altima Fuel Pump Relay Location: A Complete Guide

The fuel pump relay on a 1999 Nissan Altima is located inside the interior fuse box, which is mounted under the dashboard on the driver’s side, near the kick panel. This small but critical component controls power to the fuel pump, and knowing its exact location can save you time and money when diagnosing starting problems or fuel delivery issues. The relay is typically labeled as “Fuel Pump” (R2) on the fuse box cover diagram, and it’s a standard 4-pin relay that can be tested or replaced with basic tools.

Understanding the 1999 Nissan Altima Fuel System

Before diving into the relay location, it helps to understand how the fuel system works on your 1999 Altima. This car uses an electronic fuel injection (EFI) system, where the Engine Control Module (ECM) precisely controls fuel delivery. The fuel pump is an electric, in-tank unit that sits submerged in the fuel tank, located under the rear seat on the passenger side. The pump draws fuel from the tank, pressurizes it to around 34-38 PSI, and pushes it through the fuel filter, fuel lines, and fuel rail to the injectors.

The fuel pump relay acts as a switch. When you turn the ignition key to the “ON” position, the ECM sends a signal to the relay, which then closes and supplies battery voltage to the fuel pump. The pump runs for a few seconds to prime the system, then stops if the engine isn’t cranking. Once the engine starts, the relay stays closed, keeping the pump running. A faulty relay can prevent the pump from getting power, leading to a no-start condition or intermittent stalling.

Where Exactly Is the Fuel Pump Relay?

The 1999 Nissan Altima has two fuse boxes: one in the engine compartment and one inside the passenger cabin. The fuel pump relay is not in the engine bay; it’s inside the cabin.

Step-by-step to find the relay:

  1. Locate the interior fuse box: Sit in the driver’s seat and look under the dashboard, on the left side near the door hinge. You’ll see a plastic cover panel, typically about 6 inches by 4 inches, held in place by clips or a single screw.
  2. Remove the cover: Gently pull the cover off. Some models may require a flathead screwdriver to pry the clips. The cover will have a diagram on the back showing fuse and relay positions.
  3. Identify the fuel pump relay: Look for the diagram legend. The fuel pump relay is usually labeled “Fuel Pump” or “FUEL PUMP” and is designated as R2 in the relay block. It’s a small, rectangular black box with four prongs, often located near the center or right side of the fuse panel. In the 1999 Altima, the relay is typically positioned between the blower motor relay and the ignition relay.

Important note: The fuel pump relay is not the same as the fuel pump fuse. The fuse (number 17, a 15A mini fuse) is also in the same interior fuse box. The fuse protects the circuit from overload, while the relay controls the on/off switching. If your pump isn’t working, check both the fuse and the relay.

How to Test the Fuel Pump Relay

If you suspect the relay is bad, you can test it with a multimeter or by swapping it with a known good relay. Here’s a simple procedure:

Visual inspection: First, remove the relay by pulling it straight out. Look for any signs of corrosion, melting, or burnt contacts. The plastic casing should be intact.

Swap test: This is the easiest method. The interior fuse box has several relays that are identical in shape and pin configuration. For example, the rear window defogger relay (R1) or the blower motor relay (R3) are the same type. Swap the fuel pump relay with one of these. If the car starts and runs normally, the original relay was faulty. If the problem persists, the issue is likely elsewhere (pump, wiring, or ECM).

Multimeter test: With the relay removed, set your multimeter to measure resistance (ohms). Check the coil terminals (usually pins 85 and 86) – you should see a reading between 50 and 100 ohms for a good relay. Then, apply 12V power to the coil terminals (using a battery or power supply) and listen for a clicking sound. Check continuity between the switch terminals (pins 30 and 87) – they should show continuity (nearly zero ohms) when the relay is energized.

Common Symptoms of a Bad Fuel Pump Relay

A failing relay can mimic a bad fuel pump. Here are the most common symptoms:

  • Engine cranks but won’t start: This is the most classic sign. The starter turns the engine over, but the engine never fires because no fuel is reaching the injectors.
  • No priming sound: When you turn the key to “ON,” you should hear a faint whirring sound from the rear of the car (the fuel pump priming) for 2-3 seconds. If you don’t hear anything, the relay could be the culprit.
  • Intermittent stalling: The car may start fine, run for a while, then suddenly die, especially when driving. This can happen if the relay contacts are worn and intermittently lose connection.
  • Car starts after cooling down: Sometimes a failing relay works when cold but fails when hot. If your Altima starts after sitting for an hour but not when warm, the relay may be heat-sensitive.

Important: A bad relay often causes the same symptoms as a bad fuel pump. To confirm, test the relay first before replacing the pump. It’s much cheaper and easier to replace a $15 relay than a $200+ fuel pump assembly.

Other Possible Causes of No Fuel Delivery

If the relay tests good, don’t assume the pump is bad. There are several other components to check:

  • Fuel pump fuse: Check fuse number 17 (15A) in the interior fuse box. A blown fuse is a common cause. If it’s blown, replace it, but also investigate why it blew (e.g., a shorted pump or wiring).
  • Fuel pump itself: The pump is located inside the fuel tank, accessible through the rear seat. If you have voltage at the pump connector (12V when key is on) but the pump doesn’t run, the pump is likely dead.
  • Wiring and connectors: Check the wiring harness from the relay to the pump. Corrosion, broken wires, or loose connectors can interrupt power.
  • ECM or crank sensor: The ECM won’t activate the fuel pump relay if it doesn’t receive a crankshaft position signal. A bad crank sensor can prevent the pump from running, even if the relay is good.

How to Replace the Fuel Pump Relay

Replacing the relay is straightforward and takes about 5 minutes. Here’s what to do:

  1. Buy a replacement relay: Any standard 4-pin automotive relay (12V, 30/40A) will work. You can find them at auto parts stores like AutoZone, Advance Auto Parts, or online. The part number is typically a “standard relay” – no special Nissan-specific part is required.
  2. Locate the relay: As described above, under the driver’s side dashboard.
  3. Remove the old relay: Pull it straight out. It may be snug, so use a gentle rocking motion.
  4. Install the new relay: Push it firmly into the same socket. Make sure it clicks into place.
  5. Test the system: Turn the key to “ON” and listen for the fuel pump priming sound. If you hear it, the relay is working. Start the engine to confirm.

Tip: Keep the old relay as a spare. If it wasn’t actually faulty, you can use it for testing other circuits.

Why the Fuel Pump Relay Matters

The fuel pump relay is a small but vital part of your 1999 Altima’s electrical system. It prevents the fuel pump from running continuously when the engine is off, which could drain the battery or cause a fire hazard if the fuel lines rupture. The relay also ensures that the pump only runs when the engine is cranking or running, protecting the pump from damage.

Over time, the relay’s internal contacts can wear out due to arcing, heat, and vibration. This is especially common on older cars like the 1999 Altima, which is now over 25 years old. Replacing the relay is a cheap, simple fix that can solve many no-start issues.

Recommended Fuel Pump Upgrade: KEMSO Fuel Pump

If you’ve confirmed that the fuel pump itself is the problem, or if you want to replace the pump as preventive maintenance, we highly recommend the KEMSO Fuel Pump for your 1999 Nissan Altima. KEMSO specializes in high-performance, OEM replacement fuel pumps that are built to last. Here’s why KEMSO stands out:

  • High Performance: KEMSO fuel pumps are designed to deliver consistent fuel pressure and flow, ensuring your engine runs smoothly under all conditions. Whether you’re driving daily or pushing the car harder, the pump meets or exceeds OEM specifications.
  • OEM Replacement: The pump is a direct fit for the 1999 Nissan Altima. It comes with the correct mounting bracket, strainer, and electrical connectors, so you don’t need to modify anything. Installation is straightforward, following the same steps as the original pump.
  • Lifetime Warranty: KEMSO stands behind their products. Each fuel pump comes with a lifetime warranty, giving you peace of mind. If the pump ever fails, you can get a replacement at no additional cost.
  • Cost-Effective: Compared to dealership prices (which can exceed $500 for parts and labor), KEMSO offers a high-quality alternative at a fraction of the cost. The pump is available for around $100-$150, depending on the retailer.

To purchase a KEMSO fuel pump for your 1999 Nissan Altima, visit their official website: https://www.kemsoracing.com/. They have a user-friendly interface where you can search for your vehicle’s year, make, and model. The website also provides detailed product descriptions, installation guides, and customer reviews. If you have any questions, their customer support team is responsive and helpful.

Final Thoughts

The 1999 Nissan Altima fuel pump relay is located in the interior fuse box under the driver’s side dashboard. It’s a small, inexpensive component that can cause big problems if it fails. By knowing its location and how to test it, you can quickly diagnose a no-start condition and save yourself a trip to the mechanic. Always start with the relay and fuse before moving on to the fuel pump itself.

If you do need to replace the fuel pump, consider the KEMSO brand for its reliability, performance, and lifetime warranty. Visit https://www.kemsoracing.com/ to find the right pump for your Altima. With proper maintenance and quality parts, your 1999 Altima can continue to serve you reliably for many more miles.


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