Replacing Fuel Pump In Lexus Gx470: Step-By-Step Guide

Replacing a fuel pump in a 2004 Lexus GX470 can cost anywhere from $523 to $2,000, with parts ranging from $354 to $1,619 and labor between $158 and $357. The fuel pump is responsible for delivering gas from the fuel tank to the fuel injectors, and when it fails to do so, the car will not start or run, leading to the need for a replacement. While it is possible to replace the fuel pump yourself, it is highly recommended to hire a professional mechanic due to the risks associated with handling gasoline.

Disconnecting the battery and locating the pump assembly

Disconnecting the Battery

Before beginning any work on the fuel pump, it is essential to disconnect the negative battery cable. This step is crucial for safety, as it helps reduce the chance of a fire. Make sure to use the appropriate tools and safety equipment when working on your vehicle.

Locating the Pump Assembly

The fuel pump assembly in the 2004 Lexus GX470 is located inside the fuel tank. To access it, you will need to lower the fuel tank from the vehicle. Here are the steps to locate and access the pump assembly:

• Park your car on a level surface and engage the parking brake.
• Turn the key to the "ON" position and listen at the filler opening. The fuel pump should hum for 2-3 seconds. This step is to verify if the pump is functioning.
• Verify the location of the fuel pump relay and fuse. If the fuse is damaged, replace it with a new one of the same amperage.
• Check the fuel pump's operation. If it is working, you should be able to hear the hum. If not, and the fuse and relay are fine, check for power and ground at the pump.
• Relieve the fuel system pressure. This step is important to reduce the risk of fuel leakage.
• Drain the fuel from the tank as much as possible. Be extremely cautious when handling fuel, as it is highly flammable.
• Disconnect the filler fuel hose and the electrical connection to the old pump.
• Support the fuel tank using a jack stand and a block of wood. This will provide stability and safety while you work.
• Remove the entire pump assembly, including the pump and the fuel level sending unit. Lower the tank carefully.
• With the assembly removed, you will have access to the pump itself for replacement.

Remember to work cautiously and refer to a professional mechanic if you are unsure about any steps. Working with the fuel system requires extreme care to prevent accidents and fires.

Verifying the vehicle's fuel pump relay and fuse

To verify the fuel pump relay and fuse of a 2004 Lexus GX470, you can start by locating the fuse box. The fuse box in the Lexus GX470 (2002-2009 models) is located in the instrument panel, on the driver's side, behind a cover.

Once you've located the fuse box, you can check the fuses related to the fuel system. In the 2002-2004 models, these include the "AM1", "HEATER", "CDS FAN", "FR FOG", "DEFOG", "AIR SUS", "AC115V INV", "SEAT HEATER", "BATT CHG", "BRAKE CTRL", and "TOWING" fuses. For 2005-2009 models, the related fuses are "AM1", "HEATER", "CDS FAN", "FR FOG", "DEFOG", "AIR SUS", "AC INV", "SEAT HEATER", "OBD", "STOP", "J/B", "RR AC", "MIR HEATER", "BATT CHG", "TOWING BRK", and "TOWING".

If any of these fuses are blown, you can replace them. Additionally, you should check the fuel pump relay, which is a black plastic component with a wiring harness attached and is located either under the hood or under the dashboard near the steering wheel. If the fuel pump relay is damaged or oxidized, it will need to be replaced.

It's important to note that working with the fuel system can be dangerous, so it's recommended to take all necessary precautions to avoid starting a fire. Always disconnect the battery before performing any work on the fuel system.

Relieving the fuel system pressure and disconnecting the negative battery cable

To relieve the fuel system pressure and disconnect the negative battery cable of your 04 Lexus GX470, follow these steps:

Park your car on level ground and engage the parking brake. This is important for stability and safety when performing any work on your vehicle.

Locate the fuse box and remove the fuel pump fuse. This will disable the fuel pump and relieve the pressure in the fuel system, making it safe to work on.

Locate the negative battery terminal, which is usually marked with a "-" symbol or a black cover. Disconnect the negative battery cable by loosening the clamp bolt with a wrench and carefully lifting the cable away from the battery terminal. Ensure that the cable does not touch any metal parts of the vehicle to avoid accidental electrical shorts.

Once the negative battery cable is disconnected, secure it away from the battery using tape or a cable tie to prevent accidental reconnection.

You can now proceed with the rest of the fuel pump replacement procedure, such as draining the fuel tank and removing the fuel pump assembly. Remember to exercise extreme caution when working with gasoline, as it is highly flammable. If you are unsure or uncomfortable with any part of the process, it is best to consult a professional mechanic.

It is also important to note that relieving fuel system pressure and disconnecting the negative battery cable are just two steps in the fuel pump replacement process. Ensure that you have a proper repair manual or guide to refer to for the complete procedure.

Draining fuel from the tank and removing the pump assembly

To drain the fuel from the tank and remove the pump assembly of a 2004 Lexus GX470, follow these steps:

First, park your car on a level surface and engage the parking brake. Locate the pump assembly in the fuel tank and turn the key to the 'ON' position. Listen at the filler opening; a functioning fuel pump should hum for 2-3 seconds. Next, find and verify the vehicle's fuel pump relay and fuse, replacing the fuse if necessary.

Once you've verified the fuel pump's operation, it's time to relieve the fuel system pressure and disconnect the negative battery cable. Drain as much fuel as possible from the tank, and disconnect the filler fuel hose and the electrical connection to the old pump.

Now, support the fuel tank using a jack stand and a block of wood. You're ready to remove the entire pump assembly, which includes the pump and the fuel level sending unit. Lower the tank and remove the hose clamps and fuel line/fuel tank hose. Finally, extract the old pump from the gas tank.

This process will allow you to access and remove the fuel pump assembly of your 2004 Lexus GX470, preparing you for the next steps of replacing the fuel pump. Remember to exercise extreme caution when dealing with gasoline, as it is highly flammable.

Installing the new pump and conducting a road test

Once you have the new fuel pump, it's time to install it and test it out on the road. Here's a detailed, step-by-step guide on how to do it:

Installing the New Pump

• Compare the new fuel pump to the old one to ensure you have the correct part.
• Install the new fuel pump by connecting all the fuel lines.
• Reinstall the straps and bolts that were removed earlier.
• Reconnect the filler fuel hose and the electrical connector.
• Reconnect the negative battery cable.
• Fill the gas tank with fuel.

Conducting a Road Test

• Start the engine and let it run for a few minutes.
• Listen for any unusual noises, such as whining or humming, which could indicate a problem with the new fuel pump.
• Take the car for a test drive, paying attention to the following:

• Engine performance: Does the engine seem to be running smoothly? Are there any signs of misfiring or loss of power?
• Starting: Does the car start without any issues? Are there any delays or multiple attempts needed to crank the engine?
• Speed maintenance: Can you maintain a constant speed without the engine choking or struggling?
• Fuel efficiency: Is the car consuming fuel at the expected rate, or is there a decrease in fuel efficiency?

• If any issues are noticed during the road test, stop the vehicle in a safe location and turn off the engine. Do not continue driving if there are signs of fuel pump malfunction, as it could be dangerous.
• If the road test is successful and the new fuel pump is functioning properly, your Lexus GX470 is now ready for regular use again.

Remember, working with the fuel system can be dangerous due to the risk of fire. Always take the necessary precautions and, if possible, have a professional mechanic handle the fuel pump replacement for you.

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