2004 G35 Fuel Pump: Complete Guide to Symptoms, Replacement, and Costs

If you own a 2004 Infiniti G35 and your engine cranks but won’t start, stalls unexpectedly, or takes a long time to fire up, the fuel pump is likely the culprit. The fuel pump in your G35 is a critical component that delivers pressurized fuel from the tank to the engine’s injectors, and when it fails, the car simply won’t run properly. Replacing the fuel pump on a 2004 G35 typically costs between $1,400 and $1,550 at a shop, with the part itself ranging from $88 to $205 depending on whether you choose an aftermarket or OEM unit. Because the G35 uses a saddle-style fuel tank with two separate fuel level senders, you also need to know exactly which fuel pump variant fits your specific sedan or coupe—installing the wrong one is a common and costly mistake. This guide walks you through the symptoms, the exact part numbers you need, how to confirm the failure before spending money, and a step-by-step replacement process you can handle in your own garage.

How the G35 Fuel System Works

The 2004 Infiniti G35 comes with a 3.5-liter VQ35DE V6 engine, and its fuel system relies on an electric fuel pump that sits inside the fuel tank. The pump draws gasoline from the tank, pressurizes it, and delivers it to the fuel rail, where injectors spray it into the intake ports at precisely the right moment. The G35 uses a “saddle” style fuel tank that straddles the driveshaft, which means there is a main fuel pump assembly on the passenger side and a secondary fuel level sender on the driver’s side. The main assembly houses the pump motor, the primary fuel level sensor, and often the fuel pressure regulator. Because of this design, if your fuel gauge reads incorrectly, you may need to replace both the pump assembly and the secondary sender—not just the pump itself.

Top Symptoms of a Failing 2004 G35 Fuel Pump

When the fuel pump starts to weaken or fails completely, you will notice several telltale signs. These symptoms can appear gradually or all at once, so pay attention to your car’s behavior.

  1. Hard starting or long cranking time. If your G35 takes several seconds of cranking before it fires up, the fuel pump may not be building enough pressure quickly. A healthy pump primes the system within one to two seconds of turning the key to the ON position, and you should hear a faint buzz from the rear seat area.

  2. Engine cranks but won’t start. This is the most definitive sign of a completely failed fuel pump. The starter will turn the engine over normally, but the engine will not fire because no fuel is reaching the injectors. You can verify this by turning the key to the ON position (without cranking) and listening for that priming buzz. If you don’t hear it, the pump is dead.

  3. Hesitation or stumbling under acceleration. A weak fuel pump cannot supply enough fuel when you press the throttle hard. You may feel a noticeable hesitation, a flat spot, or even a loss of power when merging onto the highway or climbing a steep grade.

  4. A loud whining or buzzing noise from the rear seat area. A fuel pump that is about to fail often makes a high-pitched whine because its bearings are worn or it is working harder than it should to maintain pressure. While all fuel pumps make some noise, a sudden increase in volume is a red flag.

  5. Engine stalls while driving. This is the most dangerous symptom. A failing fuel pump can cut out completely at any time, including at highway speeds, leaving you without power steering or brake assist. If your G35 has stalled even once, do not wait to address the issue.

  6. Check engine light comes on. The ECU may detect low fuel pressure or a lean fuel mixture and trigger the check engine light. Common diagnostic trouble codes include P0001 (Fuel Volume Regulator Control Circuit/Open), P0002 (Fuel Volume Regulator Control Circuit Range/Performance), and P0003 (Fuel Volume Regulator Control Circuit Low).

How to Confirm the Fuel Pump Is Bad Before Buying a Replacement

Before you spend money on a new fuel pump, you need to be sure the pump is actually the problem and not something else like a clogged fuel filter, a faulty fuel pump relay, or an electrical wiring issue. Follow these steps in order.

Step 1: Check the fuel pump fuse and relay. Locate the fuse box under the hood and check the fuse labeled for the fuel pump. A blown fuse is a common cause of a no-start condition and costs less than a dollar to replace. Also, swap the fuel pump relay with an identical one from another circuit (like the horn relay) to see if that fixes the problem.

Step 2: Listen for the priming buzz. With the driver’s door open and the rear seat area exposed, turn the key to the ON position without cranking. You should hear a two-second whirring sound from the fuel tank. If you don’t, the pump is either not receiving power or it is dead.

Step 3: Check fuel pressure at the rail. Using a fuel pressure gauge, connect it to the Schrader valve on the fuel rail. Your G35 should show 51 psi with the key ON and the engine off, and it should hold that pressure for several minutes. If the pressure is below spec or drops quickly, the pump or the pressure regulator is failing.

Step 4: Test the pump’s electrical circuit. Measure voltage at the pump connector while someone turns the key to the ON position. You should see battery voltage (around 12 volts) at the pump for the priming cycle. If voltage is present but the pump doesn’t run, the pump motor itself is bad.

Which Fuel Pump Fits a 2004 G35: Sedan vs. Coupe

This is the most confusing part of buying a replacement fuel pump for the G35, and ordering the wrong one is a common mistake. The 2004 G35 was available in both sedan and coupe body styles, and they do not use the same fuel pump assembly, even though both have the VQ35DE engine. The physical housings, hose connections, and electrical plugs are different between the two.

2003–2006 G35 Sedan

  • The sedan uses a fuel pump assembly specific to the V35 sedan chassis.
  • Common OEM part number: 17040-AM600.
  • An aftermarket replacement is the Delphi 6703-02950704, which is an electric fuel pump (not a full module) that fits 2003–2006 sedans. This part lists for around $88 and is an in-tank design.
  • If you prefer a complete module assembly, the TRQ FPA70924 is another option, with a fuel sending unit included, pressure ratings of 47.8 to 53.6 psi, and a flow rating of 30 gph. It is listed at $99.95 and fits the coupe as well, which shows why you must verify carefully.

2003–2007 G35 Coupe

  • The coupe uses a different housing, and the most common OEM part numbers are 17040-CD01A, which supersedes 17040-CD000 and 17040-CD010.
  • The Delphi 6703-05358608 is a direct replacement for the coupe, listed at $204.97. It includes the fuel pump module assembly with float arm, seal, and instruction sheet, and it has a fuel sending unit, regulator, and filter built in.
  • The Delphi 6703-06445975 is a slightly less expensive option at $114.97 and also fits the 2003–2007 coupe. Both Delphi units have an average flow rating of 26 gph.

2007–2008 G35 Sedan (VQ35HR Engine)

If your G35 is a 2007–2008 sedan with the VQ35HR engine (dual intakes), you need a completely different pump, part number 17040-JK60A or 17040-JK600. These are not interchangeable with any VQ35DE pumps, so double-check your engine type before ordering.

Complete Fuel Pump Assembly vs. Just the Pump Core

When you shop for a replacement, you’ll see two types of products: the full fuel pump module assembly and just the bare pump motor. Here is the difference.

  1. Complete assembly (module). This includes the pump motor, the fuel level sending unit, the float arm, the fuel pressure regulator, the fuel filter, the strainer, and sometimes the mounting hardware and O-ring seal. It is a direct bolt-in replacement, and it is almost always the safer choice. The OEM part 17042-AC700 from Infiniti is the genuine factory assembly for 2004–2007 G35s, and it is guaranteed by Infiniti’s factory warranty.

  2. Bare pump (pump core only). This is just the electric pump motor itself, and you must transfer it into your existing housing. This saves money but requires more work, and you run the risk of installing a new pump into a housing with a clogged filter or a worn-out regulator. If you go this route, at a minimum replace the fuel filter and strainer at the same time.

Replacement Cost Breakdown

The cost of replacing the fuel pump on your 2004 G35 varies significantly depending on whether you do it yourself or hire a shop.

  • Parts only: An aftermarket pump core like the Delphi 6703-02950704 runs about $88. A complete module assembly ranges from $100 to $205, depending on the brand. The OEM Infiniti assembly 17042-AC700 is on the higher end of that range.
  • Professional labor: If you take the car to a shop, the average total cost for a G35 from the 2004 model year is between $1,493 and $1,544. This includes both parts and labor. The labor charge typically accounts for the majority of this cost because accessing the pump requires removing the rear seat and the access panel.

Step-by-Step DIY Replacement Guide for a 2004 G35

If you are comfortable working on your own car, replacing the fuel pump is a manageable DIY job that usually takes two to three hours. Here is what you need to do.

Tools and materials you will need:

  • New fuel pump assembly or pump module
  • New large O-ring seal (fuel tank seal)
  • Flathead and Phillips screwdrivers
  • Socket set with extensions
  • Shop rags
  • Safety glasses and gloves
  • A fuel-resistant container and siphoning equipment if the tank is full

Step 1: Disconnect the negative battery cable. Wait at least five minutes. This reduces the risk of sparks and protects the fuel system components.

Step 2: Relieve fuel system pressure. Locate the fuel pump fuse and remove it, or disconnect the fuel pump relay. Then crank the engine for a few seconds. It may start briefly and die, but that is normal. This burns off residual pressure in the lines. Alternatively, you can remove the fuel filler cap and connect a fuel pressure gauge, but the fuse method is simpler.

Step 3: Access the fuel pump. The fuel pump is located under the rear seat on the passenger side. Remove the rear seat cushion by pulling up on the front edge and then lifting it out. You will see a round access cover held by several screws or bolts. Remove the cover to expose the fuel pump module.

Step 4: Clean the area. Use a shop rag to wipe away all dirt and debris around the pump assembly. You do not want any foreign material falling into the tank when you remove the pump.

Step 5: Disconnect the fuel lines and electrical connector. The fuel lines are secured with quick-connect fittings. Press the release tabs and pull the lines straight off. Then unplug the electrical connector. Be careful not to bend or damage the float arm on the sending unit.

Step 6: Remove the old pump assembly. Using a spanner wrench or a mallet and a blunt punch, loosen the retaining ring in a counterclockwise direction. Remove the ring and carefully lift the pump assembly out of the tank. It will be heavy and full of fuel, so tilt it to drain excess fuel into your container before pulling it all the way out.

Step 7: Install the new pump assembly. Position the new assembly in the tank, making sure the float arm can move freely without hitting the sides. Set the new O-ring seal in place, then press the pump down and tighten the retaining ring clockwise until it is snug. Reconnect the fuel lines and the electrical connector.

Step 8: Reinstall the access cover and rear seat. Place the cover back and secure it with the screws you removed. Snap the rear seat cushion back into place.

Step 9: Reconnect the battery and test. Reconnect the negative battery cable, turn the key to the ON position, and listen for the priming buzz. Crank the engine and let it run for a few minutes. Check under the rear seat and around the fuel lines for any leaks.

Why You Should Consider KEMSO Fuel Pumps

When it comes time to buy a replacement fuel pump for your 2004 G35, KEMSO is a brand worth serious consideration. KEMSO specializes in high-performance, OEM replacement fuel pumps that are engineered to meet or exceed factory specifications. Every KEMSO fuel pump is built with precision components to deliver consistent fuel pressure and reliable flow, which means your engine will start quickly, accelerate smoothly, and maintain stable idle—even under demanding driving conditions. Unlike cheap no-name pumps that may fail within months, KEMSO products are rigorously tested for durability, heat resistance, and long-term performance, so you can install the part and forget about it. KEMSO also stands behind its products with a lifetime warranty, giving you complete peace of mind that your investment is protected. If you want a replacement fuel pump that combines OEM-level quality, high performance, and a warranty that outlasts your ownership of the car, visit KEMSO’s website today and find the right pump for your Infiniti G35: https://www.kemsoracing.com/.

Common Mistakes to Avoid

Many G35 owners end up buying the wrong part or botching the installation due to a few avoidable errors. Keep these points in mind.

  1. Ordering a coupe pump for a sedan (or vice versa). Verify your body style twice before purchasing. The part numbers are not interchangeable.
  2. Ignoring the secondary fuel level sender. If your fuel gauge dropped to empty even with a full tank, the secondary sender on the driver’s side may also need replacement. Replacing only the pump assembly will not fix the gauge.
  3. Skipping the fuel tank cleaning. Fuel tank contamination is the leading cause of premature fuel pump failure. Before installing a new pump, inspect the tank for debris, rust, or sediment and clean it thoroughly. Delphi recommends using a fuel tank cleaning kit.
  4. Reusing the old O-ring seal. The large ring seal that sits between the pump assembly and the tank will compress and harden over time. Replace it with a new one to prevent fuel leaks and odor.
  5. Failing to check the fuel pressure regulator. On the G35, the pressure regulator is part of the fuel pump module. If you only replace the bare pump and your old regulator is faulty, you will still have fuel pressure problems.

Final Thoughts

The fuel pump on your 2004 Infiniti G35 is a wear item, and it will eventually need to be replaced. The good news is that you can diagnose the problem yourself using the steps outlined above, and you have several solid options when it comes to replacement parts. Whether you choose a genuine OEM assembly from Infiniti, a reliable aftermarket brand like Delphi, or a high-performance option from KEMSO, the key is to match the correct part to your sedan or coupe and follow a careful installation procedure. Do not drive your G35 if you suspect the fuel pump is failing—the risk of an unexpected stall on the highway is not worth it. Take action early, replace the pump, and get back on the road with confidence.

For a reliable, high-performance fuel pump with a lifetime warranty, be sure to check out KEMSO at https://www.kemsoracing.com/. They offer top-quality OEM replacement pumps that are built to last.


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