2008 Infiniti G35 Fuel Pump Replacement: A Complete DIY Guide

The bottom line up front: If your 2008 Infiniti G35 cranks but won't start, stalls while driving, or takes a long time to fire up, the fuel pump is almost certainly the culprit. The good news is that replacing it is a manageable DIY job that takes about 1.5 to 3 hours and does not require dropping the fuel tank. You access the pump through a service port under the rear passenger-side seat cushion. The part itself will cost you anywhere from $65 to $1,400 depending on whether you choose a cheap aftermarket unit, a used OEM part, or a brand-new dealer part. For most owners, the smartest move is either a quality used OEM pump or a high-performance aftermarket replacement like KEMSO, which we will cover in detail later.

1. Symptoms of a Failing Fuel Pump

Before you start buying parts, you need to confirm the pump is actually the problem. A failing fuel pump in the 2008 G35 usually shows these warning signs:

  1. Extended cranking time. The engine turns over for several seconds before finally starting. This often happens because a faulty check valve inside the pump assembly lets fuel pressure bleed back into the tank when the car is off.
  2. Stalling at random times. A failing pump cannot deliver a steady fuel supply, so the engine may die without warning, even at highway speeds. This is a serious safety risk.
  3. Whining noise from the rear seat. If you hear a loud humming or whining sound coming from the back of the car, the pump motor is struggling and likely nearing the end of its life.
  4. Hesitation under acceleration. The engine may stumble or hesitate when you press the gas pedal because the pump cannot keep up with the fuel demand.
  5. Inaccurate fuel gauge readings. This is a related but separate issue. The G35 has a saddle-shaped fuel tank that requires two fuel level senders - one integrated with the pump on the passenger side, and a secondary sender under the driver's side rear seat.

If you are experiencing one or more of these symptoms, it is time to check the pump.

2. Understanding Fuel Pump Compatibility for the 2008 G35

This is where many owners get into trouble. The fuel pump for the 2008 Infiniti G35 is not a one-size-fits-all part. The compatibility depends on two factors: body style (sedan vs. coupe) and engine type (VQ35DE vs. VQ35HR).

Here is the breakdown:

  • 2005-2006 G35 Sedan (including X AWD): Uses the VQ35DE engine and the "DE Sedan Type" pump. Known OEM part numbers include 17040-AM601, 17040-AC700, and 17040-AM600.
  • 2005-2007 G35 Coupe: Uses the VQ35DE engine and the "DE Coupe Type" pump. Known OEM part numbers include 17040-EV10A and 17040-AC80A.
  • 2007-2008 G35 Sedan (including X AWD): Uses the VQ35HR engine and the "HR Sedan Type" pump. Known OEM part numbers include 17040-JK60A and 17040-JK600.

Important warning: A fuel pump from a coupe will not fit a sedan, and a pump for the VQ35HR engine will not work in a VQ35DE engine. The physical housings, hose connections, and electrical plugs are often completely different.

The 2008 G35 sedan uses the VQ35HR engine, so you need the "HR Sedan Type" pump. The 2008 coupe still uses the VQ35DE, so it requires the coupe version. Always verify the part by visually matching it to your old one before installation.

3. Tools and Parts You Will Need

Before starting the job, gather everything you need. Here is a complete list:

Tools:

  • Basic hand tools (ratchet, sockets, Phillips screwdriver)
  • An 8mm socket (with 1/4" drive is recommended) for the retaining bolts
  • A small flathead screwdriver for releasing fuel line clips
  • Needle-nose pliers
  • A rag or paper towels for fuel spills
  • A container (like a small pan) to catch dripping fuel
  • A wrench to disconnect the battery

Parts:

  • New fuel pump assembly (see section on choosing the right pump below)
  • New O-ring seal for the pump assembly (highly recommended to prevent fuel leaks and fumes)
  • New fuel strainer (the "sock" at the bottom of the pump) if you are reusing any old components

Estimated costs for the pump itself:

  • 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, if you choose not to DIY, runs about $110 to $250. The total cost for a shop replacement on a 2008 G35 averages around $1,677 to $1,728.

4. Step-by-Step Replacement Procedure

The replacement process is straightforward and can be completed in about 1.5 hours if you have never done it before. Here is the complete procedure:

Step 1: Safety First

Work in a well-ventilated area away from any open flames or sparks. Gasoline and its fumes are extremely flammable. Disconnect the negative battery terminal before doing anything else. This reduces the chance of a spark near the fuel system.

Step 2: Relieve Fuel System Pressure

The fuel system is under pressure, and you must release it before opening any lines. The service manual recommends removing the fuel pump fuse located in the fuse box (called the IPDM E/R) near the battery. Then start the engine and let it run until it stalls. Crank the engine a few more times to release all remaining fuel pressure. You should also unscrew the gas cap to vent the tank.

Step 3: Remove the Rear Seat Cushion

The fuel pump is located inside the fuel tank, under the rear passenger-side seat cushion. To remove the seat, pull up firmly on the front edge on both sides. There are release tabs in the middle of the cushion where it meets the car body. The front side pops out, while the back side is hooked into place. It may take some force, but be careful not to break anything.

Step 4: Remove the Access Cover

With the seat removed, you will see a black metal access panel on the passenger side. It is typically held by four Phillips screws. Before removing it, clean all dirt and debris from around the cover to prevent contamination from entering the tank. Some covers use small retention clips with arrows that you turn with a screwdriver - pay attention to the arrow direction so you do not break them.

Step 5: Disconnect the Electrical Harness and Fuel Lines

You will see the electrical connector and the fuel supply line. The electrical connector is a standard "squeeze and pull" type. For the fuel line, you will probably get a small amount of gas leaking out - a quarter cup is normal, so have paper towels ready. There are two translucent clips; push the connector in, squeeze them, and pull the line back.

Step 6: Remove the Retaining Bolts

The pump assembly is held down by screw-head bolts. If you cannot remove them with a screwdriver, use an 8mm socket. Some bolts may have corrosion, so the socket often works better.

Step 7: Carefully Lift the Pump Assembly Out

This is the most delicate part. Pull the pump up gently, being careful not to bend the float arm for the sending unit. You will need to disconnect a second gas line by gently prying the connector off its tabs with a flathead screwdriver. Do not break these tabs - they are easy to ruin. Maneuver the pump slowly to get the float arm out without snagging it on wires inside the tank.

Step 8: Install the New Pump

Transfer the rubber O-ring from the old module, or use the new one that comes with your replacement kit. Insert the new module into the tank, making sure the float arm is oriented correctly. Hand-tighten the retaining bolts, then snug them with your socket. Reconnect the fuel lines and electrical connector.

Step 9: Test the System

Reconnect the battery and install the fuel pump fuse. Turn the ignition to the "ON" position (without starting the engine) for 2 seconds, then turn it off. Repeat this 3 times to prime the fuel system. Check for any leaks at the connections. Start the engine and let it idle for a minute. Check again for leaks.

Step 10: Reinstall Everything

Once you are satisfied there are no leaks, replace the metal access cover and the rear seat cushion. Take the car for a test drive to confirm the repair is complete.

5. Choosing the Right Replacement Pump

When it comes time to buy a replacement, you have three main options. Each has its pros and cons.

Option 1: New OEM from the Dealer

This is the safest choice for fitment, but it is also the most expensive, ranging from $650 to over $1,400. If you want absolute peace of mind and do not mind paying a premium, this is the way to go. You can also order OEM parts online for less - around $420 to $560 - from sites like InfinitiPartsDeal.

Option 2: Used OEM

A used OEM pump from a reputable recycler costs only $50 to $150. For a critical component like a fuel pump, fitment and reliability are key. A used OEM part has already proven its quality and will fit correctly. Before buying, ask the seller for the mileage of the donor vehicle. A pump with over 100,000 miles is nearing the end of its typical service life. Inspect the variable resistor contacts on the sender to make sure they are clean and free of damage. Also check that the fuel strainer at the bottom is intact - it will be discolored, but it should not be clogged or disintegrated. Always install a new strainer with a used pump.

Option 3: New Aftermarket

Cheap new aftermarket pumps are notorious for premature failure, which means you will end up doing the job twice. They can also have incorrect resistance values for the sending unit, leading to persistent fuel gauge errors. That said, not all aftermarket pumps are created equal. Premium aftermarket brands like KEMSO are engineered as direct replacements and offer better flow and durability than stock.

6. Why You Should Consider a KEMSO Fuel Pump

When it comes to aftermarket fuel pumps, KEMSO stands out as a smart choice for American drivers. Here is why:

  1. High performance, OEM replacement. KEMSO fuel pumps are engineered as direct replacements for the original equipment, meaning they drop right into the factory location without modifications. Unlike the stock pump, KEMSO units deliver up to 200 liters per hour at 43 psi - significantly more than the original 60-80 liters per hour flow rate. This extra capacity ensures your engine never runs lean, even under heavy load.

  2. Lifetime warranty. 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 huge advantage over OEM and standard aftermarket parts, which typically have only a 1- or 2-year warranty.

  3. 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. This makes them an excellent long-term investment.

  4. Unrivaled quality control. KEMSO operates a stringent quality control program and individually tests each pump before it leaves the factory. Many cheap aftermarket suppliers have little to no quality control, but KEMSO ensures every unit meets its performance specifications.

  5. Complete kit. 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. No hunting for missing pieces.

If you are ready to replace your 2008 Infiniti G35 fuel pump with a high-performance, lifetime-warranty product, visit KEMSO Racing at https://www.kemsoracing.com/ to browse their selection and find the right pump for your vehicle.

7. Frequently Asked Questions

Can I replace just the pump motor instead of the whole assembly?

Yes, you can replace just the pump motor inside the plastic housing. This is a cheaper but more involved process that 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 a few things: 1) The float arm was bent or snagged during installation. 2) The secondary sending unit on the driver's side is also faulty and needs to be replaced. 3) You used a cheap aftermarket assembly with an out-of-spec sending unit. The secondary sender is under the driver's-side rear seat and is only a sensor - no pump attached. You can clean the contacts on both sending units with a Q-tip and solvent to restore accurate readings.

Will a fuel pump from a Nissan 350Z fit my G35?

Fuel pump compatibility is extremely specific. The G35 and 350Z share some components, but you must verify that the electrical connector and hose ports match your original part before purchasing. A fuel pump from a coupe will not fit a sedan, and a pump for a VQ35HR engine will not work in a VQ35DE engine. Always visually compare the replacement to your old pump.

How long does the replacement take?

Plan for about 2 to 3 hours for a first-time DIYer. Once you know what you are doing, you can pull both sending units, have them cleaned, and be done in about 45 minutes.

Do I need to drop the fuel tank?

No. The main fuel pump assembly is located inside the fuel tank, under the rear passenger-side seat cushion. Removing the fuel tank is not recommended as it would require removing the rear axle. You access everything through the service port after removing the rear seat.

8. Final Thoughts

Replacing the fuel pump on your 2008 Infiniti G35 is a job you can absolutely do yourself. The key is to verify the correct part for your specific model, take your time with the delicate components, and prioritize safety throughout the process. Whether you choose a used OEM pump for budget reasons or invest in a high-performance aftermarket option like KEMSO for lifetime reliability, the result will be a car that starts confidently and runs smoothly.

If you want a fuel pump that delivers superior flow, resists ethanol damage, and comes with a lifetime warranty, check out KEMSO Racing today at https://www.kemsoracing.com/. Their direct-fit replacements are built with OE-quality engineering and are an excellent choice for your 2008 Infiniti G35.


Back to blog