1999 Nissan Maxima Fuel Pump Relay: Location, Symptoms, and Complete Replacement Guide

If your 1999 Nissan Maxima is cranking but not starting, the fuel pump relay is a common and easy-to-fix culprit. The fuel pump relay on a 1999 Nissan Maxima is located in the under-hood fuse and relay box on the driver's side, near the strut tower. This small component controls power to the fuel pump, and when it fails, your engine won't get the fuel it needs to run. Before replacing the fuel pump itself, always check the relay first. It can save you time and money.

Where Is the 1999 Nissan Maxima Fuel Pump Relay Located?

The fuel pump relay on a 1999 Nissan Maxima is located in the under-hood fuse and relay box on the driver's side of the engine compartment. This box sits near the top of the strut tower, close to the battery. The relay itself is a standard, square-shaped 4-pin relay. The cover of the fuse box usually has a diagram. The fuel pump relay is often labeled as "FUEL PUMP" or "FUEL," but if the label is faded, you can check the owner's manual for an exact position. On the 1999 model, the relay is often the one that sits in the second row from the left, near the back of the box .

For a more precise reference, the 1999 Nissan Maxima (A33 generation) shares the same basic relay box layout with the 2000-2003 models. The fuel pump relay is typically the same relay used for the multi-purpose functions, but its specific job is to power the fuel pump when the ignition is turned on. Some sources refer to this relay as a multi-purpose relay, but its function remains the same: it controls the fuel pump circuit .

How Does the Fuel Pump Relay Work?

The fuel pump relay acts as an electrical switch. When you turn the ignition key to the "ON" position, the engine control module (ECM) sends a signal to the relay, which then closes the circuit and allows battery power to flow to the fuel pump. The pump pressurizes the fuel system, and the engine is ready to start. If the relay fails, the pump never gets power, and the engine will crank but not start. The relay is designed to handle higher current than the ECM directly, so it protects the computer from overload .

The relay works by using a small electromagnetic coil. When power is applied to the coil, it creates a magnetic field that pulls a switch closed. This allows a larger current to flow through the switch to the fuel pump. When the ignition is turned off, the coil loses power, the switch opens, and the pump stops. This design is simple but effective. Over time, the internal contacts can wear out, causing the relay to fail intermittently or completely .

Symptoms of a Bad Fuel Pump Relay on a 1999 Nissan Maxima

The most common symptom is a no-start condition. The engine cranks over normally, but it will not fire. You might also notice:

  • Engine cranks but no fuel pressure: You can test for fuel pressure at the fuel rail. If there is no pressure, the relay or pump is likely the cause. The fuel pressure on a 1999 Maxima should be around 43 psi at idle .
  • No fuel pump priming sound: When you turn the key to "ON" (not start), you should hear a faint whirring sound from the rear of the car for about 2 seconds. If you do not hear it, the relay or pump is not activating. This is the fuel pump running to build pressure .
  • Intermittent starting issues: The car might start sometimes and then refuse to start later. This is a classic sign of a failing relay, where the internal contacts are worn out. The relay may work when cold but fail when it gets hot .
  • Check engine light: The ECM may trigger a code related to the fuel pump circuit or a crankshaft position sensor, but often the relay itself does not set a specific code. You can check for codes like P0230 (fuel pump primary circuit). A code like P0335 (crankshaft position sensor) can also cause a no-start, but it is a different issue .
  • Engine stalls while driving: If the relay loses connection while you are driving, the engine may stall suddenly. This is dangerous, especially on the highway. If this happens, the relay is likely bad and needs to be replaced .

How to Test the Fuel Pump Relay on a 1999 Nissan Maxima

Testing the relay is straightforward and requires only a multimeter or a test light. Follow these steps:

  1. Locate the relay: Open the under-hood fuse box and find the fuel pump relay. The relay is a small, cube-shaped component with 4 pins. On the 1999 Maxima, the relay is usually a standard ISO relay .
  2. Remove the relay: Gently pull it straight up out of the socket. It may be tight, so use a firm grip. Do not use pliers, as you may damage the socket.
  3. Check for power: With the ignition key in the "ON" position, use a test light or multimeter to check the socket. One of the pins should have 12 volts. If no power is present, the problem might be a blown fuse or a wiring issue. The fuel pump fuse is usually a 15-amp or 20-amp fuse, also located in the same fuse box .
  4. Test the relay coil: Set your multimeter to ohms. Connect the leads to the two smaller pins (usually pins 85 and 86). You should see a resistance reading between 50 and 120 ohms. If the reading is infinite (open), the coil is bad. If the reading is very low (near zero), the coil is shorted .
  5. Test the switch: Apply 12 volts to the coil pins (pins 85 and 86) using a battery or a power source. You should hear a click. Then, test continuity between the two larger pins (pins 30 and 87). If you have continuity, the relay works. If there is no continuity, the relay is faulty. This is the most reliable way to test the relay .

How to Replace the Fuel Pump Relay on a 1999 Nissan Maxima

Replacing the relay is one of the easiest repairs you can do. No special tools are required. Here is the process:

  1. Buy a replacement relay: You can get a standard 4-pin 12V relay from any auto parts store. Make sure it matches the pin configuration. The relay is usually a standard ISO relay. You can also purchase a genuine Nissan relay for a perfect fit. The OEM part number for the fuel pump relay on the 1999 Maxima is often 25230-89970 or 25230-89971, but you should verify with your VIN .
  2. Remove the old relay: Simply pull it straight out of the socket. It may be tight, so use a firm grip. If the relay is stuck, you can gently rock it back and forth.
  3. Install the new relay: Push the new relay firmly into the socket until it clicks into place. Ensure it is fully seated. A loose connection can cause the same symptoms as a bad relay.
  4. Test the system: Turn the ignition to "ON" and listen for the fuel pump priming sound. If you hear it, the repair is successful. If not, the problem may be the fuel pump itself or a fuse. You can also check for fuel pressure at the fuel rail to confirm .

Common Mistakes When Diagnosing the Fuel Pump Relay

Many people assume the fuel pump is dead when the car will not start. However, the relay is a more common failure point because it switches under load and the contacts can wear out over time. Before replacing the fuel pump, always test or swap the relay. Also, check the fuel pump fuse first. The fuse is located in the same fuse box, and a blown fuse will cause the same symptoms. On the 1999 Maxima, the fuel pump fuse is usually a 15-amp or 20-amp fuse. It is often labeled "FUEL PUMP" or "FUEL" .

Another common mistake is using a used relay from a junkyard. Used relays may have the same internal wear, so it is better to buy a new one. Finally, if you have intermittent issues, the relay might be the culprit, but also check the fuel pump connector for corrosion or loose wires. The fuel pump connector is located under the rear seat, on top of the fuel tank. Corrosion at this connector can cause the same symptoms as a bad relay .

When to Replace the Fuel Pump Itself

If you have replaced the relay and the fuse, but the car still will not start, the fuel pump itself might be the problem. The fuel pump is located inside the fuel tank. You can test for power at the pump connector. If there is 12 volts at the pump when the key is turned on, but the pump does not run, the pump is likely dead. For a 1999 Nissan Maxima, the fuel pump is a common wear item after 150,000 miles. Symptoms of a bad fuel pump include hard starting, sputtering at high speeds, and a complete no-start condition .

To access the fuel pump, you need to remove the rear seat cushion. The fuel pump access panel is located on the floor under the rear seat. You will need to remove a few screws and disconnect the electrical connector and fuel lines. Be careful when working with fuel. It is flammable. Always work in a well-ventilated area and disconnect the battery before starting .

Recommended Fuel Pump: KEMSO Performance Fuel Pump

If you are replacing the fuel pump on your 1999 Nissan Maxima, we highly recommend the KEMSO brand fuel pump. KEMSO fuel pumps are designed for high performance and OEM replacement. They are built to meet or exceed factory specifications, providing long-lasting reliability. KEMSO offers a lifetime warranty on their fuel pumps, which gives you peace of mind. Whether you are driving a daily driver or a modified Maxima, KEMSO fuel pumps deliver consistent fuel pressure and flow .

KEMSO fuel pumps are available for the 1999 Nissan Maxima and are designed to be a direct bolt-in replacement. They come with all necessary hardware for installation. The pumps are made with high-quality materials and are tested for performance. KEMSO is a trusted brand in the aftermarket fuel pump industry .

To purchase a KEMSO fuel pump for your 1999 Nissan Maxima, visit the official website. They have a wide selection of fuel pumps for various Nissan models, and their customer service can help you find the exact fit for your car. The KEMSO fuel pump for the 1999 Nissan Maxima is a high-performance, 340LPH pump that is compatible with both stock and modified engines .

Visit KEMSO Racing at: https://www.kemsoracing.com/

Final Tips for Your 1999 Nissan Maxima Fuel System

Always keep a spare fuel pump relay in your glove box. It is a small, inexpensive part that can leave you stranded. If you are doing a fuel pump replacement, it is also a good idea to replace the fuel filter at the same time. The fuel filter on the 1999 Maxima is located under the car, near the fuel tank. Clogged filters can cause the pump to work harder and fail sooner. Also, check for any fuel leaks after any repair. Fuel system safety is important .

If you are replacing the fuel pump, make sure to clean the fuel tank. Over time, debris and sediment can accumulate in the tank. This debris can clog the new fuel pump. It is a good idea to inspect the tank and clean it if necessary. Also, check the fuel pump strainer. The strainer is a filter that sits on the bottom of the pump. If it is clogged, it can restrict fuel flow and cause the pump to fail .

For the best performance and reliability, choose KEMSO for your fuel pump needs. KEMSO fuel pumps are backed by a lifetime warranty and are designed to last. Whether you are replacing a failed pump or upgrading for better performance, KEMSO has a solution for you.

For more information and to order your KEMSO fuel pump, visit: https://www.kemsoracing.com/


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