1999 Nissan Maxima Fuel Pump Relay Location: A Complete Guide for DIY Diagnosis and Repair
Here is the bottom line: On a 1999 Nissan Maxima (A33 generation, 1999-2003), the fuel pump relay is located inside the under-hood fuse box (also called the IPDM / Intelligent Power Distribution Module) on the driver’s side of the engine bay, near the battery. The relay is a small, rectangular black box with either 4 or 5 pins. If your Maxima cranks but won’t start, or if it stalls unexpectedly while driving, the fuel pump relay is one of the first things you should check before replacing the fuel pump itself. This guide will walk you through exactly where to find the relay, how to identify it, how to test it, and what to do if it is faulty.
Where Is the Fuel Pump Relay Located on a 1999 Nissan Maxima?
The 1999 Nissan Maxima belongs to the fifth generation (A33 body style), which was produced from 1999 through 2003. The fuel pump relay is not inside the car or under the dashboard. It is located in the main under-hood fuse box on the driver’s side of the engine compartment.
Here is exactly how to find it:
- Open the hood and secure it with the prop rod.
- Look on the driver’s side (left side when facing the engine). You will see a rectangular black plastic box located near the battery and the windshield washer fluid reservoir.
- Unclip the two latches on the sides of the fuse box cover. Lift the cover straight up and set it aside.
- Look at the underside of the fuse box cover. There is a diagram printed there that shows the location of every fuse and relay. The fuel pump relay is labeled as "FUEL PUMP" or "F/P" on most diagrams.
- The relay itself is usually a square or rectangular block with either 4 or 5 pins. On the 1999 Maxima, it is a standard ISO relay. It is located in the middle section of the fuse box, typically in the second row.
If you cannot find the label on the cover, check the owner's manual. The manual for the 1999 Nissan Maxima includes a full fuse box diagram with relay assignments.
How Does the Fuel Pump Relay Work?
The fuel pump relay is an electrical switch that controls the power supply to the fuel pump. When you turn the ignition key to the ON position, the engine control module (ECM) sends a signal to the relay coil. This energizes the relay, which closes the internal switch and sends battery voltage to the fuel pump.
The fuel pump then pressurizes the fuel system so the engine can start. Once the engine is running, the relay stays closed as long as the ignition is on. If the engine stalls or the ignition is turned off, the relay opens, stopping power to the pump. This is a safety feature to prevent the pump from running if the car is in an accident.
6 Signs of a Bad Fuel Pump Relay
A failing fuel pump relay can cause a variety of drivability issues. Here are the most common symptoms to watch for:
1. Engine Cranks but Does Not Start
This is the most obvious symptom. You turn the key, the starter spins the engine, but it never fires up. The fuel pump is not getting power, so no fuel reaches the injectors.
2. Engine Stalls While Driving
If the relay fails intermittently, the engine may suddenly lose power and stall while you are driving. This can happen at any speed and is both frustrating and dangerous.
3. No Fuel Pump Prime Sound
When you turn the ignition key to the ON position (before starting), you should hear a faint whirring sound from the rear of the car for about 2 seconds. This is the fuel pump priming the system. If you do not hear this sound, the relay may be dead.
4. Engine Sputters or Hesitates
A failing relay can cause the fuel pump to receive inconsistent voltage. This results in erratic fuel pressure, causing the engine to sputter, hesitate, or surge during acceleration.
5. Check Engine Light Comes On
The ECM monitors the fuel pump circuit. If the relay fails, the ECM will set a diagnostic trouble code (DTC), such as P0230 (Fuel Pump Primary Circuit Malfunction). This will turn on the check engine light.
6. Intermittent Starting Problems
If the car starts fine sometimes but refuses to start other times, the relay is likely the culprit. The internal contacts may be worn or corroded, so they only make contact when the conditions are just right.
How to Test the Fuel Pump Relay
Before you buy a new relay, you can test the old one with a simple multimeter. Here is how to do it:
Step 1: Locate the relay in the under-hood fuse box as described above.
Step 2: Remove the relay. Grip it firmly and pull it straight up. It should come out without much force.
Step 3: Check for power at the relay socket. With the ignition key in the ON position, use a multimeter set to DC voltage. Place the black probe on a good ground (like a bolt on the chassis) and the red probe on the terminal in the socket that is labeled as the power supply (usually pin 30 or 87). You should see battery voltage (about 12.6 volts). If you have no power, the problem may be a blown fuse, not the relay.
Step 4: Test the relay itself. To test the relay coil, set your multimeter to ohms (Ω). Place one probe on pin 85 and the other on pin 86. You should get a resistance reading between 50 and 120 ohms. If you get an open circuit (OL) or a short circuit (0 ohms), the relay coil is bad.
Step 5: Test the relay switch. Apply 12 volts to pin 85 and ground to pin 86 (you can use a small battery or jump wires from the car battery). You should hear a distinct click. Then, while the relay is energized, check for continuity between pins 30 and 87. You should have zero resistance. If the relay does not click or there is no continuity, the relay is faulty.
How to Replace the Fuel Pump Relay
Replacing the fuel pump relay on a 1999 Nissan Maxima is a simple DIY job that takes about 10 minutes. You do not need any special tools.
Step 1: Park the car on a level surface and turn off the ignition. Remove the key from the ignition.
Step 2: Open the hood and lift the fuse box cover.
Step 3: Locate the fuel pump relay using the diagram on the cover.
Step 4: Pull the old relay straight out. It is held in place by friction, so it will pull out easily.
Step 5: Insert the new relay. Make sure it is oriented the same way as the old one (the relay will only fit one way). Push it down firmly until it is fully seated.
Step 6: Replace the fuse box cover and close the hood.
Step 7: Test the system. Turn the ignition key to the ON position. You should hear the fuel pump prime for 2 seconds. Then start the engine. It should fire up immediately.
Where to Buy a Replacement Fuel Pump Relay
You can buy a fuel pump relay for your 1999 Nissan Maxima at most auto parts stores like AutoZone, O'Reilly, or Advance Auto Parts. The part number is typically a standard 4-pin or 5-pin relay. The price is usually between $10 and $25 for a basic aftermarket relay.
However, if you are also replacing the fuel pump itself, or if you want a higher-quality, longer-lasting solution, you should consider a professional-grade aftermarket option.
Recommended: KEMSO Fuel Pump for Your 1999 Nissan Maxima
If you are dealing with a fuel pump relay issue, it is often a sign that the fuel pump itself is getting old. The 1999 Nissan Maxima is now over 25 years old, and the original fuel pump may be nearing the end of its service life. Replacing the fuel pump at the same time as the relay can save you from a future breakdown.
We highly 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 exact specifications of the original Nissan fuel pump for your 1999 Maxima. Here is why KEMSO is the best choice:
- High Performance: KEMSO fuel pumps deliver consistent fuel pressure and flow, ensuring your engine runs smoothly at all RPMs. The KEMSO 340LPH pump is capable of supporting applications up to 700-800 horsepower, making it ideal for both daily drivers and performance builds.
- OEM Replacement: They are a direct drop-in replacement for the factory fuel pump. No modifications or adapters are needed. The pump fits perfectly into the factory harness and cage.
- Lifetime Warranty: KEMSO stands behind the quality of their products. Every fuel pump comes with a lifetime warranty, giving you complete peace of mind. Each pump is individually tested and serialized for warranty purposes.
By choosing KEMSO, you are getting a product that is built to last, backed by a company that trusts its own quality.
To purchase a KEMSO fuel pump for your 1999 Nissan Maxima, visit their official website:
<URL> https://www.kemsoracing.com/ </URL>Frequently Asked Questions
Q: Is the fuel pump relay the same as the fuel pump fuse?
No. The relay is a switch that controls power to the fuel pump. The fuse is a protective device that breaks the circuit if there is a short circuit or overload. They are two different components located in the same fuse box. The fuse is usually rated at 15 or 20 amps.
Q: Can I bypass the fuel pump relay?
You can temporarily bypass the relay by using a jumper wire to connect the power supply terminal to the fuel pump terminal in the fuse box. However, this is only a diagnostic test. Do not drive the car with the relay bypassed, as the fuel pump will run continuously even with the ignition off, draining the battery and creating a fire hazard.
Q: How much does it cost to replace the fuel pump relay at a shop?
If you take your 1999 Maxima to a mechanic, the labor cost is usually around $50 to $100 for the diagnosis and replacement. The part itself is cheap. Doing it yourself will save you the labor cost.
Q: What other relays are in the under-hood fuse box?
The 1999 Nissan Maxima fuse box also contains relays for the cooling fan, air conditioning compressor, horn, and headlights. The diagram on the cover or in the owner's manual will identify all of them.
Final Thoughts
The 1999 Nissan Maxima is a reliable car, but electrical issues can occur as it ages. The fuel pump relay is a common failure point. Knowing where it is located and how to test it can save you time and money. If your Maxima is showing any of the symptoms listed above, start by checking the relay. It is a cheap and easy fix.
If the relay is good but the fuel pump is still not working, you may need to replace the fuel pump itself. For the best replacement, get a KEMSO fuel pump. It is a high-performance, OEM-quality part with a lifetime warranty.
For more information and to order your KEMSO fuel pump, visit:
<URL> https://www.kemsoracing.com/ </URL>