Replacing Fuel Pump On 2003 Trail Blazers: Hour-Long Fix

Replacing the fuel pump on a 2003 Trailblazer is a complex task that requires specific tools and a good amount of time. The process involves removing the rear driver's side seat, trimming the door jamb and B pillar, and dealing with fuel lines and electrical connections. It is important to relieve fuel pressure, disconnect the battery, and take precautions to avoid sparks and potential fires. The fuel pump is located inside the fuel tank, and dropping the tank is often necessary for access. Some people have attempted to cut a hole in the floorboard above the fuel pump to avoid dropping the tank, but this method is controversial and may require additional sealing and safety measures to prevent fuel leaks and carbon monoxide issues. The average cost for a professional fuel pump replacement on a 2003 Trailblazer is between $788 and $953, but some people choose to do it themselves to save money.

Removing the cross bar

To remove the cross bar, you will need to first raise the car with a floor jack and support it with two jack stands on the drive side frame. You can also use a ramp instead. Next, you will need to siphon the fuel gas from the gas tank so that the tank is not too heavy to remove later. You can use a tool from AutoZone or Advance Auto Parts to do this.

Now, you can remove the frame cross bar under the fuel tank. You will see two fuel tank braces too. Spray WD-40 on the braces to prevent rust. Before removing the fuel tank braces, make sure to use a piece of plywood board underneath the tank and use a floor jack to support the tank.

Use a 15mm socket to loosen and remove the screw on the drive side brace bar. The passenger side brace bar is not screwed in but inserted and rotated 90 degrees to hold it in place. Once the drive side brace bar is removed, simply release and rotate the bar to remove it from the frame. The front brace bar is easy to remove, but the rear one is a little harder. If it is difficult, you can simply bend the bar to get clearance.

Disconnecting the negative battery terminal

The negative battery terminal is connected to the vehicle's engine, body, and chassis. Disconnecting it first will prevent any tools from accidentally touching the engine or body and short-circuiting against the positive terminal. This could cause physical injury or a fire.

When to Disconnect the Car Battery

It is best to disconnect your car battery when:

• Recharging or replacing the battery
• Conducting maintenance
• The vehicle will not be in use for several months

How to Disconnect the Car Battery

• Ensure the engine is turned off.
• Locate the battery. It is usually under the hood, but sometimes it is in the trunk.
• Identify the battery terminals. The negative terminal has a "-" symbol and the positive terminal has a "+" symbol and a red cover.
• Using a wrench, loosen the nut on the negative terminal and remove it from the battery post. Ensure the cable is not touching the terminals.
• Loosen and remove the nut on the positive terminal.

Reconnecting the Battery

• Place the battery on the battery tray, ensuring it is level.
• Reinstall the battery, making sure the bolts are tight to prevent vibrations and displacement.
• Reconnect the positive red cable to the positive terminal, then reconnect the negative black cable to the negative terminal.
• Secure the battery fasteners tightly on the battery posts.
• Test the battery by starting the vehicle and turning on electronics such as the radio and headlights.

Additional Tips

• If you are only going to remove one terminal, remove the negative terminal first.
• Always reconnect the positive terminal before the negative terminal.
• Minor arcing when reconnecting the negative terminal is normal and not a cause for concern.

Removing the fuel lines

To remove the fuel lines of a 2003 Trailblazer, you will need a fuel line disconnect tool. These can be purchased cheaply at O'Reilly, AutoZone, or Pep Boys.

To remove the fuel lines, you will first need to relieve the pressure in the lines. With the engine running, pull the relay for the fuel pump, and the engine will die within a few seconds. Crank the engine a few times to relieve the pressure.

Then, press in the clips (blue on the filter) and squeeze the other lines to disconnect the fuel lines. No special tools are needed for this step.

Note that fuel may come out of the lines if there is still pressure in the system.

Disconnecting the electrical connections

• Park the vehicle on a level surface and engage the parking brake. Place wheel chocks around the wheels for added safety.
• Remove the negative battery terminal to disconnect the power supply. This is an important safety precaution to prevent any accidental electrical shorts during the procedure.
• Locate the fuel pump electrical connector. It is usually found near the fuel tank, often in the rear of the vehicle. Refer to your Trailblazer's service manual or consult a mechanic if you are unsure about its location.
• Before disconnecting the electrical connector, it is essential to relieve the fuel system pressure. To do this, access the fuse box and remove the fuel pump relay. Attempt to start the engine, and it should die within a few seconds as the fuel pump is no longer receiving power. Crank the engine a few times to ensure all pressure is released.
• With the pressure relieved, you can now safely disconnect the electrical connector from the fuel pump. This process may vary depending on the specific connector design in your Trailblazer. Gently pull on the connector to detach it from the fuel pump. If it is challenging to remove, carefully wiggle or twist it while pulling to loosen any corrosion or buildup that may be holding it in place. Be cautious not to damage the connector or the wires.
• Once the electrical connector is detached, set it aside in a safe place, ensuring it does not come into contact with any fuel or flammable substances.
• At this point, you may need to remove additional components or wiring harnesses connected to the fuel pump to fully access it. Refer to your Trailblazer's repair manual or seek guidance from a qualified mechanic for specific instructions on removing these components.
• With the electrical connections and any necessary components disconnected, you can now proceed to the next steps of replacing the fuel pump, such as removing the fuel tank straps and lowering the tank.

Remember to work cautiously and refer to the appropriate repair manuals or seek professional assistance if needed. Working with fuel systems can be dangerous, so ensure you take the necessary safety precautions.

Removing the straps

To remove the straps, you will need a size 15 socket, an extension, and a 1/2-inch ratchet. Loosen the straps with the ratchet, and then jiggle the rearmost strap to get it out of the way. The front strap should come right off.

Frequently asked questions