Replacing Fuel Pump In '03 Chevy Truck: Step-By-Step Guide

If you're experiencing issues with your 2003 Chevy truck's performance, such as poor acceleration or difficulty starting the engine, it may be time to replace the fuel pump. This complex process involves several steps, including relieving fuel line pressure, lifting the truck, removing the fuel filler neck, disconnecting fuel tank lines and power lines, and finally, installing a new fuel pump module. While it is possible to undertake this task independently, it is essential to prioritise safety and work in a well-ventilated area free from heat sources, sparks, and open flames.

How to change the fuel pump in a 2003 Chevy Truck

The fuel pump is located in the fuel tank

• Siphon out as much gas as possible from the tank.
• Remove the fuel tank fill pipe.
• Remove the evaporative emission (EVAP) canister.
• If equipped, remove the fuel tank shield bolts and the shield itself.
• Disconnect the fuel feed/return pipes from the fuel tank pipes.
• Cap the fuel and EVAP pipes to prevent contamination.
• Place a suitable jack under the fuel tank.
• Remove the fuel tank strap bolts and straps.
• Lower the fuel tank to access the electrical connections.
• Disconnect the fuel sending unit connector position assurance (CPA) connector and the electrical connectors.
• Completely lower the fuel tank and place it in a suitable work area.

Once the fuel tank is removed, you can access the fuel pump through the top opening and replace it with a new one.

Siphon out excess gas before removing the fuel tank

When replacing the fuel pump in a 2003 Chevy truck, it is important to siphon out excess gas before removing the fuel tank. This is because the fuel pump is located inside the fuel tank, and removing the tank with a full load of gas can be extremely heavy and difficult to manage.

There are several methods to siphon out the excess gas. One way is to use a hose and your mouth, although this can be unpleasant and potentially dangerous. A safer method is to use a siphoning pump or a clear hose, which can be inserted into the rubber tube coming from the filler door to the tank. This will allow you to reach the bottom of the tank and pump the gas out into containers or a fuel caddy. You can also try disconnecting a line and turning the key on, while knocking on the bottom of the tank, to trick the pump into working and get the gas out.

Another option is to use an electric fuel pump and slide a hose from the pump into the vent hose beside the filler neck on the tank. This will reach the bottom of the tank and allow you to pump out the gas. If you are using an electric pump, you may need to connect a battery charger to the truck battery.

Removing the bed of the truck is also an option, as it provides easier access to the tank and fuel pump.

Disconnect the fuel feed/return pipes

To disconnect the fuel feed/return pipes from the fuel tank pipes of your 2003 Chevy truck, you will need to locate the fuel filler neck and the fuel tank. The fuel filler neck is found on the driver's side of the tank and above the frame. It is a large-diameter hose connected to the tank with a hose clamp.

Firstly, use a stubby flat-head screwdriver to loosen the hose clamp, and the fuel filler neck should come off easily. Next, move to the passenger side of the tank and start disconnecting all the lines going into the top of the tank. Begin with the vapor line, which is connected to the charcoal overflow tank, and then move on to the larger supply line. These lines have connectors that you'll need to squeeze at the base to detach them. Be prepared for some fuel spillage, even if it's just a little, as there will still be some pressure left in the line. Ensure you are wearing safety goggles to protect your eyes from any gasoline splash.

There will be two more lines above the vapor and supply lines that you will need to disconnect as well. These lines have white connector clips that need to be pushed in simultaneously as you pull on the hose.

Once all the lines are disconnected, cap the fuel and evaporative (EVAP) pipes to prevent possible fuel/EVAP system contamination.

Disconnect the power lines to the fuel pump

To disconnect the power lines to the fuel pump of a 2003 Chevy truck, follow these steps:

Firstly, ensure you are working in a well-ventilated area, free of any heat sources, sparks, and open flames. Do not smoke while working around fuel sources.

Now, locate the fuel tank. The fuel pump is situated inside the fuel tank, so you must remove the tank to access the pump. Before you do this, relieve the fuel line pressure by pulling the fuel pump relay from the fuse box. Then, start the vehicle and let it run until it shuts down.

Next, lift the truck using a jack and place it on jack stands in the manufacturer's recommended locations on level ground. If you don't have access to a lift, use four jack stands and lift the entire truck.

Now, remove the fuel filler neck from the tank. This can be found on the driver's side of the tank and above the frame. Loosen the hose clamp with a stubby flat-head screwdriver and remove the fuel filler neck.

Move to the passenger side of the tank and disconnect all the lines going into the top of the tank. Start with the vapor line, then move on to the larger supply line. These lines have similar connectors that you'll squeeze at the base to disconnect. Be prepared for some fuel to spill from the lines.

Finally, disconnect the power lines to the fuel pump. There are two quick-release electrical plugs on top of the fuel tank. Disconnect these plugs from the pump, and you will have successfully disconnected the power lines to the fuel pump.

Remove the gas tank straps and lower the tank

To remove the gas tank straps and lower the tank of a 2003 Chevy truck, follow these steps:

First, support the gas tank with a jack. Remove the four 13mm bolts from the fuel tank shield. Pull down the shield. Next, remove the 15mm bolt from the fuel tank strap. You can now lower the fuel tank until the electrical connections are accessible.

Remove the fuel sending unit connector position assurance (CPA) connector. Disconnect the fuel sending unit and pressure sensor electrical connectors. Now you can completely lower the fuel tank. With the aid of an assistant, place the fuel tank in a suitable work area.

Note: Before removing the gas tank straps, it is recommended to siphon out as much gas as possible from the tank. Additionally, ensure that you have the necessary tools, such as a jack, sockets, ratchet, and extension, as well as new gas tank straps.

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