Replacing Fuel Pump Wires: A Step-By-Step Guide

Replacing a fuel pump wiring harness is a simple process that can be done in a few steps. It is essential to replace the old wiring harness with a new one supplied with your new fuel pump module to ensure the proper functioning of your new fuel pump. Before beginning the process, it is important to prioritise safety by wearing safety glasses and gloves, and keeping a fire extinguisher nearby.

Disconnect the negative battery terminal

Disconnecting the negative battery terminal is the first step in replacing a fuel pump wiring harness. It is important to take safety precautions when performing this task. Wear safety glasses and gloves to protect yourself from acid and electrical hazards. Remove any metal jewellery to prevent accidental short circuits.

To disconnect the negative battery terminal, first locate the battery. It is typically under the hood on either side of the engine bay. You can check the owner's manual if you are unsure of the battery location. Once you have located the battery, identify the terminals. The positive terminal is usually marked with a plus (+) sign and may have a red cover. The negative terminal will have a minus (-) sign and often has a black cover.

Now, use a wrench to loosen the nut or bolt on the negative terminal by turning it counter-clockwise. You only need to loosen it enough so that the terminal can be wiggled off by hand. Once the terminal is removed, tuck it away in a place where it cannot accidentally come into contact with the negative post of the battery, such as behind the battery.

It is important to note that disconnecting the battery can reset the car's computer and clear error codes. It may also reset other systems, requiring you to reset the clock or reprogram radio presets.

Disconnect the fuel pump harness from the tank

Disconnecting the fuel pump harness from the tank is a delicate and potentially dangerous process, so it is important to be cautious and prepared. Before beginning, ensure you are wearing safety glasses and gloves, and have a fire extinguisher nearby.

Firstly, disconnect the negative battery terminal. This is a crucial safety step as it will prevent any accidental electrical discharges during the process. Now, you can begin to disconnect the fuel pump harness from the tank. Remove about a foot of tape and black plastic conduit from the harness. Be careful not to confuse the harness with the fuel pressure sensor connector, as they may look similar.

Once you have successfully disconnected the fuel pump harness from the tank, you can proceed to the next steps of replacing the wiring. It is important to be cautious and methodical throughout this process to ensure a secure connection and avoid any potential hazards.

It is important to note that this process may vary slightly depending on the specific vehicle and fuel pump setup, so it is always recommended to refer to a professional or manufacturer's instructions if you are unsure.

Match old wiring to new

When replacing the fuel pump wiring harness, it is important to match the old wiring to the new wiring. This is because your new fuel pump may not work properly if you don't.

Firstly, make sure you are wearing safety glasses and gloves, and have a fire extinguisher close by. Disconnect the negative battery terminal and then disconnect the fuel pump harness from the tank. Remove about a foot of the tape and black plastic conduit from the harness, ensuring you are not dealing with the fuel pressure sensor connector.

If the old wiring is not identical to the new wiring, refer to the diagram that comes with the new wiring. This will help you match the old to the new. Now you can start cutting. Cut the first pair of wires about two inches away from the electrical connectors. Then, stagger the rest of your cuts by about an inch and a half and strip the wires. Crimp the vehicle wiring to the new wiring harness with the supplied connectors on all wires, ensuring you don't trap any insulation between the electrical connector crimp.

Finally, shrink the insulation with a heat gun to secure the connections, keeping this away from any fuel. When the glue begins to come out of the connector, your seals are weather-tight. To finish up, install the black plastic conduit and re-tape the wires.

Cut and strip the wires

To cut and strip the wires, you'll need to start by cutting the first pair of wires about two inches away from the electrical connectors. Be sure to use wire cutters or a similar tool designed for this purpose. You don't want to damage the wires or, worse, injure yourself. After cutting the first pair, stagger the rest of your cuts by about an inch and a half. With your cuts made, it's now time to strip the insulation from the wires. You can use a wire stripper for this task, which will help you remove the insulation without damaging the wire itself. It's important to be careful and precise during this step. Once the wires are stripped, you'll be able to see the exposed conductors, which will be connected to the new wiring harness.

At this point, it's crucial to handle the wires with care to avoid any damage to the exposed conductors. The next step is to crimp the vehicle's wiring to the new wiring harness. Ensure you use the supplied connectors on all wires. When crimping, be mindful not to trap any insulation between the electrical connector crimp. A firm and secure connection is essential for optimal performance and safety. Once the wires are crimped, it's a good idea to use a heat gun to shrink the insulation and further secure the connections. Keep the heat gun away from any fuel sources, and be patient as you work. You'll know the connections are weather-tight when the glue begins to come out of the connector.

With the connections secure, you're almost done with this stage of the process. Now, carefully install the black plastic conduit and re-tape the wires. This will help protect the connections and ensure the wires are safely managed. It's important to follow these steps carefully and refer to any diagrams or instructions provided with your specific fuel pump module. Each vehicle and fuel pump may have slight variations, so having a clear understanding of the wiring layout is essential before proceeding.

By taking your time and following the proper procedures, you can confidently replace the fuel pump wires, ensuring a secure connection for the life of your vehicle. Remember to wear the appropriate safety gear and have a fire extinguisher nearby as a precaution.

Crimp and insulate the wires

Crimping wires is a delicate process and must be done correctly to avoid dodgy connections. Firstly, you will need to strip the wires by about an inch and a half to expose the metal strands. Then, you can twist the wires together and wrap a single strand of wire around the joint to hold the strands together.

Next, you will need to use a crimping tool to secure the connection. Ensure that you use the correct type of crimping tool for the size of your wires. There are various types of crimping tools available, such as plier-type crimpers, bootlace crimpers, and tunnel crimpers. It is important to choose the right type of crimping piece that will fit your wires snugly.

After crimping, it is essential to insulate the connection to protect it from the surrounding fuel and to prevent short circuits. You can use heat shrink tubing or electrical tape for insulation. Make sure to choose a type of insulation that is fuel-resistant and will not dissolve or deteriorate when exposed to gasoline or ethanol. Test the insulation material by dipping it in gasoline or petrol to ensure it is fuel-resistant.

Additionally, you can use a soldering iron to solder the connection before applying the insulation. Soldering provides a more secure connection and is less prone to cracking than crimping. However, it is not commonly used in automotive wiring due to cost and production speed considerations.

Frequently asked questions