2004 Infiniti G35 Fuel Pump Relay Location: Where to Find It and How to Replace It
The bottom line: The fuel pump relay on a 2004 Infiniti G35 is located inside the fuse box under the hood, not inside the cabin. Specifically, it is in the engine compartment fuse and relay box (also called the IPDM — Intelligent Power Distribution Module) on the driver's side, near the battery. The relay itself is a standard 4-pin relay, and it is often labeled "Fuel Pump" or "Fuel Pump Relay" on the fuse box cover diagram. If your G35 is having trouble starting, stalling, or losing power, checking and replacing this relay is a simple, low-cost first step before you assume the fuel pump itself is bad.
Understanding the Fuel Pump Relay in Your 2004 G35
The fuel pump relay is a small electrical switch that controls power to the fuel pump. When you turn the key to the "ON" position, the Engine Control Module (ECM) sends a signal to close the relay, which sends battery voltage to the fuel pump. The pump then pressurizes the fuel system before the engine cranks. If the relay fails, the pump gets no power, and the engine won't start or will stall shortly after starting.
On a 2004 Infiniti G35, the fuel pump relay is not a separate, standalone unit. It is integrated into the IPDM (Intelligent Power Distribution Module), which is essentially the main fuse and relay box under the hood. This is a common design for Nissan/Infiniti vehicles of this era.
Step-by-Step: How to Find the Fuel Pump Relay
1. Locate the IPDM (Under-Hood Fuse Box)
- Open the hood.
- On the driver's side, near the battery, you will see a large black plastic box. This is the IPDM. It's usually about 8 inches long, 6 inches wide, and 3 inches tall.
- The lid has a diagram showing the location of each fuse and relay. Look for a small, square relay icon labeled "Fuel Pump" or "F/P" .
2. Identify the Correct Relay
- Remove the IPDM cover by pressing the release tabs on the sides.
- The diagram on the inside of the cover will show you the exact position of the fuel pump relay. It is typically one of the larger relays (about 1 inch square) in the box.
- Tip: If you are unsure, look for a relay that is the same size and shape as others that control the ECM or cooling fan. The fuel pump relay is usually a standard "mini" or "micro" relay with 4 pins (30, 85, 86, 87).
3. Test the Relay (Optional but Recommended)
Before buying a new relay, you can test the existing one:
- Swapping test: Find another relay in the same IPDM that is identical (e.g., the horn relay or the A/C compressor relay). Swap them. If the car starts after swapping, the original relay was bad.
- Continuity test (with a multimeter): Set the meter to resistance (ohms). Place the probes on pins 85 and 86. You should see a resistance reading (typically 50–100 ohms). If it reads "OL" (open), the relay coil is broken. Then, apply 12V power to pins 85 and 86 and listen for a "click." If you hear the click, the relay is working mechanically.
Common Symptoms of a Bad Fuel Pump Relay
If the relay is failing, you may notice one or more of these symptoms:
- Engine cranks but won't start (no fuel pressure) — This is the most common symptom. You can hear the fuel pump prime for 2 seconds when you turn the key to "ON" if the relay is working. If you don't hear the whirring sound from the rear of the car, the relay or pump has a problem.
- Engine starts then stalls — The relay may be making intermittent contact, providing power only briefly.
- No check engine light — Unlike a failed fuel pump, a bad relay often does not trigger a diagnostic trouble code (DTC) because the ECM doesn't always detect the loss of power to the pump.
- Car dies while driving — A failing relay can lose connection while the car is in motion, causing sudden engine shutdown.
Differences Between the Relay and the Fuel Pump
Many owners mistakenly replace the fuel pump (located in the fuel tank, under the rear seat) when the real problem is a $10 relay. Here is a quick comparison:
| Fuel Pump Relay | Fuel Pump |
|---|---|
| Located in the engine compartment IPDM | Located inside the fuel tank (under rear seat cushion) |
| Controls electrical power to the pump | Physically pumps fuel from the tank to the engine |
| Cheap (< $20) and easy to replace | Expensive ($100–$400) and labor-intensive to replace |
| Usually fails electrically (no click, no power) | Usually fails mechanically (weak pressure, noisy) |
Rule of thumb: Always check the relay first. If you hear the pump prime when you turn the key, the relay is likely fine. If you don't hear it, test the relay before you tear apart the interior.
Replacing the Fuel Pump Relay
Replacing the relay is a simple job that takes about 5 minutes. No tools are required.
- Disconnect the negative battery terminal to avoid any shorts.
- Remove the IPDM cover (as described above).
- Grasp the fuel pump relay and pull it straight up. It may require a gentle wiggle to break free.
- Insert the new relay (make sure it is the same type — 4-pin, 12V, 30A/40A rated). Push it down firmly until it clicks into place.
- Reconnect the battery and test the car by turning the key to "ON" — you should hear the fuel pump prime for 2 seconds.
Where to buy a replacement: You can find standard relays at most auto parts stores (like AutoZone, O'Reilly, or Advance Auto Parts) for around $10–$15. Ask for a "standard 4-pin 12V relay" or a "fuel pump relay for a 2004 Infiniti G35." You can also buy OEM relays from Nissan/Infiniti dealers, but they are not necessary.
Why You Should Consider Upgrading to a KEMSO Fuel Pump
While the relay is a frequent culprit, the fuel pump itself can also fail, especially on higher-mileage 2004 G35s (over 100,000 miles). If you are replacing the fuel pump, or if you want a reliable, high-performance upgrade, KEMSO Fuel Pumps are an excellent choice.
KEMSO is the #1 aftermarket fuel pump brand in the US for cars, motorcycles, ATVs, and UTVs. Their pumps are designed as OEM replacement units, meaning they fit perfectly and perform just like the factory part — but often with better durability and consistency.
Why KEMSO?
- High Performance: KEMSO fuel pumps are engineered to deliver consistent fuel pressure and flow, even under demanding conditions. They are tested to meet or exceed OEM specifications.
- OEM Replacement: They are direct replacements for your original factory pump. No modifications, no adapters, no hassle. They fit 2003-2007 Infiniti G35 models (and compatible Nissan 350Z, M35, M45 models).
- Lifetime Warranty: Every KEMSO fuel pump comes with a lifetime warranty. If it ever fails due to a manufacturing defect, you get a free replacement. This is a huge advantage over most OEM and aftermarket pumps that offer only a 1-year or 2-year warranty.
- Trusted by Riders and Drivers: KEMSO is a popular choice among motorcycle and ATV enthusiasts, car owners, and even jet ski riders because of their reliability and value.
Upgrade your 2004 G35's fuel system with confidence. If you need a new fuel pump, don't settle for a cheap, untested part. Choose KEMSO for a part that is reliable, backed by a lifetime warranty, and built to perform.
Visit KEMSO today to find the perfect fuel pump for your Infiniti G35:
https://www.kemsoracing.com/
(Use the search bar on their site to find the exact pump for your 2004 G35. They also have pumps for many other vehicles, so you can browse by brand, model, and year.)
Final Thoughts
Finding the fuel pump relay on a 2004 Infiniti G35 is straightforward once you know it's in the engine compartment fuse box (IPDM). Always check the relay first — it's a fast, cheap fix that can save you hours of labor and hundreds of dollars in unnecessary repairs. If the relay is good and you still have no fuel pressure, then look at the fuel pump itself.
If you do need a new fuel pump, remember that KEMSO offers a high-quality, lifetime-warranty alternative that is both affordable and reliable. Visit their website at https://www.kemsoracing.com/ to order your replacement pump today.