Replacing The Motor In Your Fuel Pump: A Step-By-Step Guide

Replacing the motor in a fuel pump is a complex task that requires careful attention to safety precautions. Fuel pumps are small electric motors that transfer fuel from the fuel tank to the engine, and they can fail due to various reasons such as wear and tear, contamination, or electrical faults. Before attempting any replacement, it is crucial to ensure that the pump is indeed faulty and that other potential issues, such as a clogged fuel filter or fuel line restrictions, have been ruled out. The process of replacing the motor involves relieving the fuel system pressure, locating and removing the fuel tank, disconnecting the old pump, and reassembling the system with a new pump while ensuring all safety measures are followed to prevent accidents or damage.

Prepare your workspace and safety equipment

When preparing to replace the motor in your fuel pump, it is important to ensure your workspace is safe and that you have the correct safety equipment. Here is a detailed guide on how to prepare:

Workspace Setup:

Firstly, ensure your vehicle is parked on a level surface and set the parking brake. If your vehicle has a manual transmission, place the transmission in gear. It is crucial to block the front wheels to prevent the vehicle from rolling when you raise the rear wheels.

Next, you will need to raise the rear of the vehicle with a jack and support it with a minimum of two jack stands. Ensure the jack stands have the proper weight rating to handle the weight of your vehicle. Never crawl under a vehicle that is only supported by a jack.

Safety Equipment:

Before starting any work on the fuel pump, it is vital to disconnect the battery to cut off the power supply and reduce the risk of electrical shock and damage to the electrical system. Always disconnect the negative battery cable first.

It is also important to relieve the fuel system pressure to prevent fuel from spraying out. You can do this by covering the Schrader valve on the fuel rail with a rag and pressing the valve stem. Alternatively, you can disconnect the fuel pump fuse or relay and run the engine until it stalls. Remember to wear safety goggles and gloves during this process to protect yourself from fuel splatter.

As you will be working with flammable liquids, it is crucial to ensure your workspace is well-ventilated to minimise the risk of fire and inhalation of harmful fumes. Keep the area free from any sources of ignition, such as sparks or heaters, and do not smoke. Always have a fire extinguisher rated for fuel fires within reach in case of emergencies.

Before beginning any work, gather all the necessary tools and equipment, including a new fuel pump, fuel filter, and any other components specific to your vehicle. It is also recommended to have a container ready to catch any fuel that may spill during the replacement process.

Additional Precautions:

If possible, drain or siphon out most of the fuel from the tank to reduce the risk of spills and make the fuel tank lighter and easier to handle. Remember to drain the fuel into an approved container, such as a metal or plastic gas can, and never an open bucket.

Always wear safety glasses, gloves, and appropriate clothing to protect yourself from fuel spills and splashes. Consult your vehicle's service manual or online tutorials for additional guidance and to familiarise yourself with the process before starting.

Drain the fuel tank

Before removing the fuel tank, it is important to drain as much fuel as possible from the tank. This will lighten the tank, making it much easier to handle, lower, and lift back into place. Some fuel tanks have a drain plug at the bottom, which can be loosened with a wrench to start the fuel flow. If your tank does not have a drain plug, you will need to use a hand siphon pump or a hose to drain the tank.

To use a hand siphon pump, insert the hose down the filler neck and use the pump to start the siphon action. Drain the fuel into an approved container, such as a metal or plastic gas can, and seal the container once the tank is empty. It is important to never use an electric drill-powered pump, as the sparks may ignite the fuel, and to never suck on the hose, as gasoline is poisonous and the fumes can be harmful.

Alternatively, you can use a hose and a container to collect the fuel. Insert the hose into the tank and suck on the other end to start the flow of fuel. This method does not require any specialized equipment, but it carries a risk of inhaling toxic fumes, and fuel can get into your mouth, which is dangerous.

Another option is to use a compressed air system. This method requires tools like an air compressor, a fuel tank adapter, and a fuel line. Connect the fuel line to the tank adapter and the adapter to the air compressor. Once you are set up, start the compressor, and the pressure will force the fuel out of the tank.

Finally, you can use a manual pump to drain the fuel tank. This process requires a manual pump, a fuel tank adapter, and a fuel line. Connect the fuel line to the tank adapter and the adapter to the manual pump, then start the pump to force the fuel out of the tank. Keep a container handy to collect the fuel as it is pumped out. When you are done, disconnect the fuel line, turn off the pump, and store the tools safely.

Disconnect the battery

Disconnecting your car battery is a relatively simple process that can be done without a mechanic or auto shop. Here is a step-by-step guide on how to do it safely:

Turn Off the Ignition

Before beginning, turn off your car engine. Never attempt to disconnect your car battery while the car is on. It is also recommended to use safety equipment, such as gloves and safety goggles, if possible.

Locate the Battery and Terminals

Pop the hood of your car and locate the car battery. Car batteries are large, block-like components with two large cables attached to them near the engine bay's surface. They are typically located under the hood, but in some cases, they may be in the trunk or under the rear seat. Consult your vehicle's manual if you are unsure.

Once you've located the battery, identify the terminals. The negative terminal is marked by a "-" symbol and is usually black, while the positive terminal is marked by a "+" symbol and is usually red.

Disconnect the Negative Terminal

Remove any plastic caps from the battery terminals. Then, use a wrench to loosen the nut on the negative terminal by turning it counterclockwise. After it's loose, carefully remove the negative connector cable from the battery and set it aside, ensuring it doesn't touch the battery again.

Disconnect the Positive Terminal

Repeat the same process for the positive terminal. Ensure that the positive and negative terminals do not touch each other or any metal surface. You may need to isolate the positive cable end by wrapping it in a non-conductive material, such as a towel.

At this point, your battery should be completely disconnected. However, if you need to remove the battery for maintenance or replacement, follow the next steps:

Loosen and Remove the Battery Hold-Down

The battery hold-down keeps the battery in place while driving. Locate the fasteners and loosen or remove them with a wrench, then carefully remove the battery. Be mindful of its weight, as car batteries can weigh between 30-50 pounds. Place the battery on a dry, flat surface.

By following these steps, you can safely disconnect your car battery, which is an important step when performing maintenance or replacing the fuel pump motor.

Remove the fuel tank

Removing the fuel tank from a vehicle can be a challenging task. Here is a step-by-step guide to help you through the process:

Prepare the necessary tools and equipment: Ensure you have the right tools for the job, including various sizes of open-end wrenches, screwdrivers, and special tools for disconnecting fuel line fittings. You will also need a jack, jack stands, a pump for removing fuel, fuel-rated containers, rags, and a fire extinguisher.

Choose a suitable work area: It is important to work on a flat surface, preferably a concrete driveway, as asphalt can be damaged by fuel spills. If concrete is not available, hard, compacted soil can be used.

Gather repair parts in advance: Check if the required repair parts are readily available, especially if you need to order specific components like fuel level sensing units.

Get assistance: This task is easier and safer with an extra pair of hands. An assistant can help hand you tools and respond in case of any accidents.

Disconnect the battery: Before proceeding, remove the ground cable from your vehicle's battery to prevent any accidental sparks.

Drain the fuel tank: Use a pump to extract the fuel from the tank. Place a container large enough to hold the fuel (12-20 gallons) underneath the vehicle, and carefully drain the fuel into it. Seal any openings to prevent vapors from escaping.

Chock the front wheels: Ensure the vehicle is securely parked and cannot roll by chocking the front wheels.

Lift the vehicle: Use a hoist or a jack to raise the vehicle. Make sure it is lifted high enough to access the brackets or straps that secure the fuel tank. Support the vehicle with jack stands.

Clean the outside of fuel lines and connectors: Use compressed air to blow away any debris and accumulated dirt from the fuel lines and wiring connectors. You may need to do this a few times, using a small stiff brush to loosen stubborn dirt.

Optional: Place a work mat underneath: For added comfort and to prevent losing small parts like fasteners, nuts, and washers, place a work mat, plywood, or even a scrap piece of carpet underneath the vehicle.

Disconnect the fuel tank wiring harness: Detach the fuel tank wiring harness connector from the auto body's harness connector. If your vehicle has a ground wire screw on the chassis, remove it.

Remove the fuel lines: Carefully detach the fuel lines from the gas tank. You may need a specialized tool to separate "quick disconnect" fittings. Refer to your vehicle's service manual for specific instructions.

Disconnect the filler and vent pipes: Wipe the filler and vent pipes with a soft towel before disconnecting their tubes from the tank. Note that you may need to lower the tank slightly to access these connections.

Unhook the filler neck: There are usually two types of filler necks. For a one-piece neck, remove the screws around it. For a two- or three-piece assembly, loosen the clamp and detach the neoprene hose. Ensure the fuel hose at the top of the tank has enough room to drop down when the tank is lowered.

Locate and loosen the fastening system: Typically, there are two straps wrapped around the fuel tank, fastened with bolts to a bracket on the vehicle's frame. Loosen these bolts just enough so that the tank is still supported, and carefully lower the tank as you finish loosening them.

Remove the support straps: Pull the gas tank support straps out and away from the tank so that they do not obstruct the removal process. Be careful not to kink or damage the straps.

Remove the tank: With the straps out of the way, carefully remove the tank from underneath the vehicle by dragging it sideways. Now you can perform the required maintenance or repairs.

Remember to work with caution and always refer to your vehicle's service manual for specific instructions pertaining to your make and model.

Reassemble the fuel system

Once you have installed the new fuel pump, it is time to reassemble the fuel system. First, put a new filter screen on the pump. A new screen usually comes with the pump. If you are replacing the entire fuel pump module assembly, it will come with a new inlet filter screen and fuel level sending unit.

A new gasket or seal should also be installed on the top plate to prevent leaks. Inspect the fuel and vent hoses. If any of the hoses are cracked, leaking, or damaged, replace them with new hoses. Make sure to use high-pressure hoses approved for EFI use. New hose clamps are also recommended.

Never reuse an old filter screen. Install a new screen on the new pump before putting it into the tank. Once the pump has been installed in the tank, reinstall the fasteners or locking ring that holds the pump cover to the fuel tank. Reconnect the wiring harness to the pump, ensuring all the connectors are clean and tight. You can use dielectric grease on the connectors to keep out moisture that could cause corrosion later on.

Reconnect the EVAP system vapor hoses to the fuel tank, and the fuel line to the fuel pump outlet. Make sure all hoses are correctly routed. Raise the fuel tank back into place and reinstall the support straps that hold it in place. Reconnect the fuel filler hose to the fuel tank inlet. Make sure all clamps are tight.

Add several gallons of fuel to the tank and check for leaks. The tank should be at least 1/4 full to provide enough fuel for proper pump lubrication and cooling before starting the vehicle. Install a new fuel filter in the fuel supply line. Do not reuse the old in-line fuel filter as it may be dirty and restrict fuel flow to the engine.

Finally, start the engine and check all fuel line connections for leaks. If there are no leaks, you're done!

Frequently asked questions