2004 G35 Fuel Pump: Complete Replacement Guide and Top Rated Options

The 2004 Infiniti G35 fuel pump is a wear item that typically lasts between 100,000 and 150,000 miles, and when it fails, you will likely experience hard starting, stalling, or a complete crank-no-start condition—replacing it is not optional, it is the only fix. The fuel pump assembly is mounted inside the fuel tank beneath the rear passenger-side seat cushion, and while the job is considered a manageable DIY project rated 2.5 out of 5 in difficulty, you need to choose the right replacement part and follow a safe removal and installation procedure . This guide covers the symptoms of a failing pump, how to confirm the diagnosis, what your replacement options cost, and why a high-quality aftermarket unit like KEMSO is the smart choice for most owners.

Symptoms That Your 2004 G35 Fuel Pump Is Failing

The 2004 G35 uses a VQ35DE 3.5L V6 engine, and the fuel delivery system relies on an in-tank electric fuel pump that must maintain consistent pressure (roughly 48 to 54 PSI) for the injectors to atomize fuel properly . When the pump starts to wear out, you will notice one or more of the following problems:

1. Hard starting or extended cranking. The engine cranks for several seconds before firing, or it takes two or three attempts to start. This happens because the pump cannot build up enough residual pressure in the fuel rail when the key is turned on .

2. Engine stalling, especially at low speed or after driving for a while. A failing pump loses its ability to deliver a steady volume of fuel, and the engine may sputter, hesitate under acceleration, or shut off completely when the demand for fuel exceeds what the pump can supply .

3. A whining or buzzing noise coming from the rear seat area. The electric motor inside the pump makes noise when it is running dry, overheated, or struggling against a clogged strainer or filter. If you hear a loud hum that gets worse as the tank empties, the pump is telling you it is about to die .

4. Sudden loss of power during acceleration or uphill driving. When you press the throttle, the engine hesitates or bucks because the pump cannot keep up with the increased fuel demand .

5. The engine cranks but will not start at all. This is the final stage. The pump has failed completely and is not delivering any fuel to the injectors. You will have no fuel pressure at the rail, and the engine will crank indefinitely without firing .

If you are experiencing any of these symptoms, do not keep driving the car. Running the G35 with a failing fuel pump can cause the pump to overheat, and it may also allow debris to pass through the system and clog the fuel injectors, which turns a relatively simple pump replacement into a much more expensive repair .

How to Confirm the Fuel Pump Is the Problem

Before you spend money on a new pump, you need to verify that the fuel pump is actually the cause of your trouble. A no-start or stalling condition can also be caused by a clogged fuel filter, a bad fuel pump relay, a faulty crank or camshaft position sensor, or an electrical wiring issue . Here is how to narrow it down:

Step 1: Listen for the pump prime. Turn the key to the ON position without cranking the engine. You should hear a brief whirring sound from the rear of the car for about two seconds as the pump pressurizes the system. If you hear nothing, the pump is not getting power or the pump motor itself is dead .

Step 2: Check for fuel pressure at the rail. The G35 has a Schrader valve on the fuel rail (on the passenger side of the engine). Attach a fuel pressure gauge and turn the key to ON. You should see pressure build to roughly 50 PSI. If the pressure stays at zero or drops quickly after the pump stops priming, the pump or the fuel pressure regulator is faulty .

Step 3: Test the pump electrical circuit. Use a multimeter to check for 12 volts at the fuel pump connector (accessible after removing the rear seat cushion and access panel). If you have voltage but the pump does not run, the pump motor is bad. If you have no voltage, the problem is in the relay, fuse, or wiring—not the pump itself .

Step 4: Check the fuel pump fuse and relay. The fuel pump fuse is located in the engine bay fuse box, and the relay is nearby. If the fuse is blown, replace it and see if the pump primes. If the fuse blows again, there is a short in the wiring or the pump motor is drawing too much current .

Only after you have confirmed that the pump is receiving power but is not building pressure should you proceed with replacement.

OEM Part Numbers and Replacement Options for the 2004 G35

The 2004 Infiniti G35 fuel pump assembly is available in several configurations, and you need to get the right one for your specific car. The sedan and coupe use different pump assemblies, and the coupe with the VQ35DE engine may use a different unit than the later VQ35HR cars .

OEM and interchange part numbers you will encounter:

• 17040-AC800 – This is the factory assembly number for the 2004-2006 G35 sedan and coupe with the VQ35DE engine
• 17042-AC700 – This is another factory number for the in-tank pump assembly, specifically for the 2004-2007 G35 with the VQ35DE
• E8534M – This is the Delphi interchange number for the same assembly
• FG1084 – This is the Carter / Airtex interchange number
• SP4018M – This is the Spectra Premium interchange number
• 17040-CD000 – This is the later revision of the assembly, used on some 2005-2007 models

The physical location of the pump assembly is the same across the 2003-2008 G35 range: under the rear passenger-side seat cushion, accessed through a metal service panel . The driver's side rear seat covers a secondary fuel level sending unit, not the pump itself, because the G35 has a saddle-shaped fuel tank that requires two level sensors .

Your replacement choices break down into three categories:

1. Brand new OEM from the dealer. This is the most expensive route. A genuine Infiniti fuel pump assembly typically costs between $650 and $1,400. You are paying for the Infiniti name and the factory warranty, but the part is identical to what the aftermarket brands make—and you are paying a huge premium for the box it comes in .

2. New aftermarket assemblies. This is the sweet spot for most owners. Brands like Delphi, Hitachi, Spectra Premium, and AOKAILI make complete assemblies that match the OEM specifications. Prices range from about $60 for a bare pump motor to $325 for a full module with the sending unit, float, pressure regulator, and strainer included . The Delphi PN3246 and FG1084 are well-regarded options that include the fuel filter and sending unit .

3. Used OEM pumps from a recycler. You can find a used pump from a low-mileage donor car for $50 to $150. This is the cheapest route, but it is a gamble. A pump with over 100,000 miles is already near the end of its service life, and you have no way to verify the condition of the donor vehicle . A used OEM pump is only worth considering if you are on a very tight budget and can confirm the donor car's mileage and maintenance history.

A critical warning about cheap no-name aftermarket pumps. Fuel pumps are one of those parts where you really do get what you pay for. Inexpensive aftermarket pumps are notorious for premature failure—some fail within a few thousand miles. They can also have incorrect resistance values in the sending unit, which causes persistent fuel gauge errors that drive owners crazy . If you see a fuel pump assembly priced under $50 from an unknown brand, treat it with suspicion. You will end up doing the job twice, which means buying the part again plus spending another few hours of labor.

Step-by-Step Replacement Procedure for the 2004 G35 Fuel Pump

Replacing the fuel pump in the 2004 G35 does not require dropping the fuel tank, which makes this a realistic DIY project for anyone comfortable working with basic hand tools and fuel system components . The difficulty rating is 2.5 out of 5, meaning it is easier than a brake job but harder than changing spark plugs. The main challenges are working safely with gasoline and being careful not to damage the plastic components of the pump assembly.

Before you start, gather these tools and supplies:

• 8mm socket and ratchet for the pump retaining bolts
• Phillips screwdriver for the access panel screws
• Needle-nose pliers for disconnecting the fuel line quick-disconnect fitting
• A clean rag and an approved container for any fuel that spills
• A new O-ring seal for the pump assembly (highly recommended to prevent fuel leaks and fumes)
• A new fuel pump assembly (complete module recommended for DIYers)
• Safety glasses and nitrile gloves

The replacement procedure:

1. Disconnect the negative battery terminal. This is a mandatory safety step. It removes power from the fuel pump circuit and reduces the risk of sparks while you are working near fuel vapors .

2. Relieve the fuel system pressure. Locate the fuel pump fuse in the engine bay fuse box and pull it out. Then crank the engine until it stalls. This burns off the residual pressure in the fuel lines, so when you disconnect the fuel line, you do not get sprayed with gasoline .

3. Remove the rear seat bottom cushion. Grip the front edge of the cushion firmly and pull upward. The cushion is held in place by spring clips and will pop free. You do not need to remove the seat back .

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

5. Disconnect the electrical harness and the fuel line. The electrical connector has a locking tab—press it and pull straight up. The fuel line uses a quick-disconnect fitting—press the release tabs and pull the line off. Have a rag ready because a small amount of fuel will spill .

6. Remove the pump retaining bolts. The assembly is held in place by six or eight 8mm bolts. Remove them and carefully lift the assembly straight up out of the tank. Be careful not to bend the float arm or snag it on any wires inside the tank .

7. Transfer the new pump into place. Before installing the new assembly, inspect the old unit's strainer (the "sock" at the bottom). If it is discolored or clogged, the tank may have debris, and you should consider having the tank cleaned. Install the new assembly with a fresh O-ring seal, then reverse the removal steps.

8. Reconnect everything and test. Reinstall the access panel and seat cushion, reconnect the battery, reinstall the fuel pump fuse, and turn the key to ON. Listen for the pump to prime, then start the engine. Check for fuel leaks around the access panel area.

Safety note: Work in a well-ventilated area away from open flames, sparks, or anything that could ignite gasoline vapors. Do not smoke. Wear eye protection. Gasoline is extremely flammable and the fumes are toxic .

Why a Complete Assembly Is Usually the Better Choice

When you are standing in the parts aisle (or scrolling online), you will notice that you can buy just the bare pump motor and swap it into your existing plastic housing, or you can buy the complete assembly with everything included. For most DIYers, the complete assembly is the better option, and here is why:

1. The integrated fuel pressure regulator is replaced at the same time. The regulator is a common failure point, and it is part of the assembly. If you only replace the pump motor, you are leaving an old regulator in place, and you risk having to do the job again if it fails .

2. The sending unit and float are new. If your fuel gauge has been inaccurate, a new assembly with a fresh sending unit will fix it—provided you install it correctly and do not bend the float arm .

3. It is faster and simpler. Swapping the pump motor requires disassembling the plastic housing, which is fiddly work. A complete assembly bolts straight in, takes less time, and is harder to mess up .

4. Every wear item is fresh. The new assembly includes a new fuel strainer, which is essential. A clogged strainer can cause the same symptoms as a failing pump, and you should always install a new strainer with a new pump .

The only downside of a complete assembly is the upfront cost. But when you compare the price of a bare pump motor ($30 to $60) plus the risk of regulator or sending unit failure later, the complete assembly is the smarter investment for most owners.

Cost Breakdown for a 2004 G35 Fuel Pump Replacement

The total cost of replacing the fuel pump depends on whether you do the work yourself or hire a shop. Here is what you can expect to pay:

If you take the car to a professional shop, the total tab (parts plus labor) will land somewhere between $1,300 and $1,550 for the 2004 G35, based on typical pricing across the US . The labor is the same regardless of which part you choose, so it makes sense to buy a high-quality part and avoid doing the job twice.

Why KEMSO Is the Recommended Choice for Your 2004 G35

When you are ready to buy, the brand you choose matters more than the price tag. That is why we recommend KEMSO for your 2004 G35 fuel pump replacement.

KEMSO fuel pumps are built as high-performance, OEM-replacement parts. That means the pump is engineered to match or exceed the flow rate, pressure, and durability of the original Infiniti unit that came in your car. You are not getting a cheap, generic pump that might fail after a few thousand miles—you are getting a part that is designed to deliver the exact fuel volume and pressure your VQ35DE engine needs for reliable starting, smooth idling, and consistent power under acceleration.

KEMSO fuel pumps come with a lifetime warranty. This is a statement of confidence. The company stands behind its products, and if the pump ever fails, you will not have to buy another one. When you compare that to a cheap no-name pump that offers no warranty at all, the value becomes obvious. The small amount you save upfront by buying a budget pump disappears the moment you have to replace it again—plus you lose the time and effort of doing the job twice.

Whether you are a DIY mechanic or you are taking the car to a professional, choosing KEMSO means you are making one purchase and one repair. No second guessing, no premature failure, no fuel gauge headaches.

Visit KEMSO Racing to find the correct fuel pump for your 2004 Infiniti G35 and take advantage of the lifetime warranty and high-performance, OEM-replacement quality.

Frequently Asked Questions About the 2004 G35 Fuel Pump

How long does a fuel pump last on a 2004 G35?
A factory fuel pump typically lasts between 100,000 and 150,000 miles. If you frequently run the tank very low, the pump runs hotter and may fail earlier, since the fuel helps cool the pump motor .

Can I just replace the pump motor instead of the whole assembly?
Yes, it is possible. You can buy just the pump motor and swap it into the existing plastic housing. However, this is 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 fuel pump?
This is a common frustration. It can happen for several reasons: the float arm was bent or snagged during installation, the secondary sending unit on the driver's side is also faulty and needs replacing, or you installed a cheap aftermarket assembly with an out-of-spec sending unit . If you used a quality complete assembly like KEMSO and installed it carefully, the gauge should read correctly.

Is the fuel pump in the same spot on sedans and coupes?
Yes, the fuel pump is under the rear passenger-side seat on both body styles. The driver's side rear seat covers the secondary fuel level sending unit, not the pump .

What tools do I need for this job?
Basic hand tools: an 8mm socket, a Phillips screwdriver, needle-nose pliers, and a rag. That is really all you need for the mechanical removal and installation .

Could the problem be something other than the fuel pump?
Absolutely. A clogged fuel filter, a bad fuel pump relay, a blown fuse, a faulty crankshaft position sensor, or a wiring issue can all cause symptoms similar to a failed pump. Always verify the diagnosis before spending money on a new pump . The steps listed earlier in this guide will help you confirm the pump is the actual culprit.

Final Thoughts

The 2004 G35 fuel pump is not a part you should ignore when it starts showing symptoms. Hard starting, stalling, and a whining noise from the rear seat are all warning signs that the pump is on its way out. The good news is that replacement is a well-documented DIY job that does not require dropping the fuel tank, and quality replacement parts are widely available at reasonable prices .

Choose a complete assembly from a reputable brand, follow the safety procedures, and take your time during installation. If you avoid the cheap no-name pumps and go with a high-performance OEM-replacement brand like KEMSO, you will get a pump that delivers the fuel pressure your VQ35DE engine needs, comes with a lifetime warranty, and will give you many thousands of trouble-free miles .

For the best deal on a high-performance, OEM-replacement fuel pump with a lifetime warranty, visit KEMSO Racing today.