2004 Infiniti G35 Fuel Pump Location: Where It Is and How to Access It Without Dropping the Tank

The fuel pump on a 2004 Infiniti G35 is located inside the fuel tank, underneath the rear passenger-side seat cushion. You do not need to drop the fuel tank to access it. By removing the rear seat bottom and a small metal access panel, you can reach the entire fuel pump assembly through a service port in the top of the tank . A secondary fuel level sending unit sits under the driver’s-side rear seat, but it is only a sensor, not the pump itself .

This guide walks you through the exact location, what you will see when you get there, the tools you need, and the step-by-step process to remove and replace the pump on your 2004 G35. It also covers common mistakes, cost expectations, and why choosing the right replacement part matters for long-term reliability.

Where the Fuel Pump Is Located on a 2004 G35

The 2004 Infiniti G35 uses a saddle-shaped fuel tank, which means the tank spans across the driveshaft tunnel. Because of this design, the vehicle uses two separate units inside the tank :

  • Main fuel pump assembly – under the rear passenger-side seat cushion. This is the unit that pressurizes fuel and sends it to the engine .
  • Secondary fuel level sending unit – under the rear driver’s-side seat cushion. This unit only measures fuel level; it does not contain a pump .

When people search for the fuel pump location, they are almost always looking for the passenger-side unit. If you are experiencing crank-no-start, stalling, or a whining noise from the rear seat area, the passenger-side pump is the one you need to inspect .

What You Need Before You Start

Replacing the fuel pump on a 2004 G35 is rated as a 2.5 out of 5 difficulty job . It is manageable for a DIYer with basic mechanical skills, but you must be careful working with gasoline. Here is what you need:

Tools:

  • 8mm socket for the pump retaining bolts
  • Ratchet and extension
  • Phillips screwdriver
  • Needle-nose pliers
  • Rags or shop towels
  • A fuel-safe container for residual fuel
  • Safety glasses and gloves

Safety items:

  • Work in a well-ventilated area, away from open flames or sparks
  • Disconnect the negative battery terminal before starting
  • Relieve fuel system pressure before opening anything

Step-by-Step: How to Access the Fuel Pump

Follow these steps in order. Taking shortcuts on the safety steps can lead to injury or fire.

Step 1: Relieve fuel system pressure. Locate the fuel pump fuse in the fuse box. Pull the fuse, then start the engine and let it run until it stalls. Crank the engine two or three more times to clear remaining pressure from the lines .

Step 2: Disconnect the battery. Remove the negative battery terminal. This prevents any electrical sparks while you are working near fuel .

Step 3: Remove the rear seat cushion. Pull up firmly on the front edge of the rear seat bottom. There are two clips that hold the seat in place. If they are broken, simply lift the seat out .

Step 4: Remove the access panel. On the passenger side, you will see a black metal access cover. It is typically held by four Phillips screws. Remove the screws and lift the panel off .

Step 5: Disconnect the electrical harness and fuel line. You will see the top of the fuel pump assembly. Disconnect the electrical connector. Then disconnect the quick-disconnect fuel line. Have a rag ready because some fuel will spill .

Step 6: Remove the pump assembly. Use the 8mm socket to unscrew the six to eight bolts holding the pump assembly to the tank. Carefully lift the assembly straight out. Be careful not to bend the float arm or snag it on wires inside the tank .

Step 7: Install the new pump. Installation is the reverse of removal. It is highly recommended to replace the large rubber O-ring seal to prevent fuel leaks and fumes .

Step 8: Test the system. Reconnect the battery, install the fuel pump fuse, and turn the ignition to the “ON” position for two seconds. Turn it off, then repeat three times to prime the system. Check for leaks, then start the engine .

What You Will See When You Open the Access Panel

When you remove the rear seat and access cover, you will see the top of the fuel pump module. It looks like a round plastic flange with an electrical connector and a fuel line attached. The assembly sits inside the tank and extends down into the fuel .

The fuel pump assembly includes several integrated components :

  1. Pump motor – the electric pump that pressurizes fuel
  2. Fuel pressure regulator – maintains consistent pressure
  3. Fuel level sending unit – measures fuel level on the passenger side
  4. Fuel strainer (sock) – filters debris at the bottom of the tank
  5. Float arm – moves with fuel level to send the gauge signal

When you replace the pump, you have two options: replace just the pump motor inside the plastic housing, or replace the entire assembly. Replacing the whole assembly is faster, simpler, and ensures the integrated regulator and sending unit are fresh. Replacing only the motor is cheaper but requires disassembling the unit .

Common Mistakes to Avoid During Replacement

Many G35 owners run into the same problems when replacing their fuel pump. Here is what to watch out for:

1. Bending or snagging the float arm. When you lift the old pump out, the float arm can catch on wiring inside the tank. If you bend it, your fuel gauge will read incorrectly after reinstalling .

2. Choosing a cheap aftermarket pump with an out-of-spec sending unit. Some aftermarket assemblies have incorrect resistance values for the sending unit, which causes persistent fuel gauge errors. A used OEM pump or a quality aftermarket brand avoids this issue .

3. Reusing the old O-ring. The large rubber seal between the pump flange and the tank should always be replaced. A worn O-ring will leak fuel and fumes into the cabin .

4. Forgetting about the secondary sending unit. If the fuel gauge is still wrong after replacing the passenger-side pump, the driver’s-side sending unit may also be faulty and need replacement .

5. Not checking the strainer condition. The fuel strainer will likely be discolored, but it should be intact. A heavily clogged or disintegrated strainer suggests the pump was overworked or the tank has debris. Always install a new strainer with the new pump .

Fuel Pump Pressure Specifications for 2004 G35

The stock G35 fuel pump is typically rated to deliver fuel at a pressure range of 40 to 60 psi under normal operating conditions . For most driving situations, this range is sufficient for the VQ35DE engine .

If you are planning to modify your G35 for higher performance, such as turbocharging or supercharging, the stock pump may not be able to keep up. Pushing a stock pump to sustain 58 psi continuously can cause premature wear, reduced lifespan, or failure . For high-performance builds, you need a high-flow fuel pump, upgraded fuel lines, and regulators .

For a stock 2004 G35, the factory fuel pump delivers a maximum of 90 to 120 liters per hour . This is sufficient for daily driving and spirited street use.

Cost of Replacing a Fuel Pump on a 2004 G35

The cost varies significantly depending on the part source. Here is a breakdown of typical prices :

  • New OEM from dealer: $650 to $1,400+
  • New OEM online: $420 to $560
  • New aftermarket: $65 to $325
  • Used OEM: $50 to $150
  • Shop labor: $110 to $200

If you are doing the job yourself, plan on spending between $65 and $560 depending on the part you choose. If you take it to a shop, add labor. A full replacement typically takes 2 to 3 hours for a DIYer .

Choosing the Right Replacement Pump

For a critical component like a fuel pump, fitment and reliability are key. Cheap new aftermarket pumps are notorious for premature failure, causing you to do the job twice . Here is what to consider:

1. OEM vs. aftermarket. Genuine Infiniti parts are produced to factory specifications and have gone through stringent quality checks . Used OEM pumps from reputable recyclers have already proven their quality and will fit correctly . A pump with over 100,000 miles is nearing the end of its typical service life, so check mileage .

2. Part number compatibility. The 2004 G35 uses specific part numbers depending on your trim and engine. The part number 17042-AC700 fits 2004-2007 G35 models with the 3.5L VQ35DE engine . The part number 17042-5Y700 fits 2003-2005 G35 models . Always verify the part number for your specific VIN before purchasing .

3. Compatibility with the 350Z. The G35 and 350Z share platforms and engines . A pump from a 2006 350Z will often work in a 2006 G35 Coupe, but you must verify the part number and visually confirm the electrical connector and hose ports are identical .

Why Choose KEMSO Fuel Pump for Your G35

When it comes to replacing the fuel pump on your 2004 Infiniti G35, you have several options: OEM parts from the dealer, cheap no-name aftermarket pumps, or premium brands like KEMSO. KEMSO stands out as a strong choice for American drivers looking for performance and value.

KEMSO fuel pumps are engineered as direct OEM replacements, meaning they drop right into the factory location without modifications . Unlike the stock pump, KEMSO units are designed for superior flow and durability. They deliver up to 200 liters per hour at 43 psi, which is significantly more than the original 60-80 liters per hour flow rate of a standard pump . This extra capacity ensures your engine never runs lean, even under heavy load.

Every KEMSO fuel pump comes with a serialized body that guarantees a lifetime warranty. If it ever fails due to a manufacturing defect, KEMSO replaces it for free . This is a massive advantage over OEM and standard aftermarket parts, which typically have only a 1- or 2-year warranty .

KEMSO fuel pumps are also ethanol and E85 compatible. With more gas stations switching to E15 or E85 blends, having a pump that resists ethanol degradation is essential. KEMSO’s Viton-lined components prevent the swelling and cracking that destroy standard rubber seals .

When you buy a KEMSO fuel pump, you get everything you need for the installation: the pump, gradient density fuel strainers, flex hoses, Viton O-rings, wiring connectors, and clamps . Each pump is individually tested before it leaves the factory .

For a 2004 G35 that needs a reliable, long-lasting fuel pump, visit KEMSO Racing at https://www.kemsoracing.com/ to see their full lineup of high-performance fuel pumps with lifetime warranty coverage.

Frequently Asked Questions

Do I have to replace the whole assembly, or can I just replace the pump motor? You can replace just the pump motor inside the plastic housing. This is cheaper but more involved and requires disassembling the unit. For most DIYers, replacing the entire assembly is faster, simpler, and ensures the integrated fuel pressure regulator and sending unit are fresh .

Why is my fuel gauge still wrong after replacing the pump? This is a common problem. It can be caused by three things: the float arm was bent or snagged during installation, the secondary sending unit on the driver’s side is also faulty, or you used a cheap aftermarket assembly with an out-of-spec sending unit .

What is the part under the driver’s side rear seat? That is the secondary fuel level sending unit. Because the G35 has a saddle-shaped tank, it needs two sensors to get an accurate fuel reading. The driver’s side unit is only a sensor; the pump is on the passenger side .

Final Thoughts

The 2004 Infiniti G35 fuel pump location is straightforward: under the rear passenger-side seat cushion, accessed through the service port on top of the fuel tank . You do not need to drop the tank, and the job is manageable with basic hand tools .

When the pump fails, you will know it. Symptoms include engine sputtering at high speeds, loss of power during acceleration, difficulty starting, a whining noise from the fuel tank area, and a check engine light related to fuel system pressure .

Take your time with the replacement, follow the safety steps, and choose a quality replacement part. A reliable fuel pump is essential to keeping your G35 running smoothly for years to come. For a high-performance, OEM-replacement fuel pump with a lifetime warranty, check out KEMSO Racing at https://www.kemsoracing.com/ before you make your purchase decision.


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