Replacing Inline Fuel Pumps: A Step-By-Step Guide For Beginners

Replacing an inline fuel pump is a messy job that requires careful preparation and a good understanding of car mechanics. It is important to dress appropriately and ensure your workspace is well-ventilated as you will be working around fuel and fuel vapours. Before you begin, gather the necessary tools, including a ratchet wrench set, tubing, wrenches, hose clamp pliers, a bolt or wooden dowel, and a fire extinguisher. It is also crucial to disconnect the negative battery cable and ensure the vehicle is turned off. The process involves disconnecting the fuel tank hose, plugging the hose with a bolt, and disconnecting the vapour-return hose if present. It is important to wipe up any spilled fuel and replace the fuel hose if it is frayed or cracked. The next steps include disconnecting the outlet line to the carburettor, removing the old fuel pump, and cleaning the mounting surface. When installing the new pump, apply a gasket sealer, attach the fuel outlet line, and connect the fuel inlet hose and vapour-return hose. Finally, reconnect the battery ground cable, start the vehicle, and check for any leaks.

How to relieve fuel system pressure

Before you can start working on the fuel system of your vehicle, you need to relieve the pressure in the fuel system. The following methods can be used to relieve fuel system pressure:

• Most fuel injection fuel system models (most modern vehicles) use a Schrader valve (similar to a tire's air valve). You can find the valve near the fuel rail, which holds the fuel injectors. Use a shop rag to cover the valve and a small screwdriver to depress the valve. Catch the squirt of fuel with the rag. Then disconnect the battery negative (black) cable.
• Another method is to remove the fuel pump fuse (in the fuse box) or the fuel pump relay (under the dashboard or under the hood), or unplug the ignition coil electrical connector. Then start the engine, and let it stall. Crank the engine for a few seconds, and then disconnect the battery.
• Some vehicles (specifically Ford) have an inertia switch (check your car owner's manual or repair manual). You can unplug this switch and start the engine. Let it stall. Then crank the engine for a few seconds, and disconnect the battery.
• If you have a car with an access door to the fuel pump under the back seat or inside the trunk, start the engine, then unplug the electrical connector. Let the engine stall, and disconnect the battery.
• After properly relieving the fuel system pressure, remove the fuel filler neck cap to relieve pressure inside the tank as well.

Now, you are ready to start working on your fuel pump. First, locate the fuel tank in your vehicle. You may find the tank at the rear, under the vehicle, behind a body panel, or under the rear seat. Check your vehicle car owner's manual or repair manual, if necessary.

Some vehicle models provide a fuel pump access door, to save you from dropping the fuel tank to service the fuel pump. So check your car owner's manual or repair manual. Or check under the back seat or the trunk of your car for a small, bolted door. You may see an electrical connector on it.

If your vehicle doesn't have this access door, safely secure the car on a couple of jack stands. Block each front wheel with a wooden block to prevent the vehicle from rolling.

Before proceeding to work on the fuel tank, check that no parts or components will interfere when you are attempting to drop the tank. Otherwise, remove these components. Check your car repair manual if necessary.

Then, place the floor jack under the fuel tank with a piece of wood between the jack saddle and the fuel tank to prevent damaging the tank. Raise the jack just enough to rest the jack's saddle against the fuel tank.

Then, proceed to remove the bolts from the two fuel-tank holding straps (some tanks use mounting screws around the flange instead). You may need to use a ratchet with a long extension to reach these bolts—and a swivel joint in some cases, to reach the bolts from an angle.

Once you've removed the straps out of the way, check to see if you can disconnect the fuel filling hose or fuel lines from the fuel tank at this point. Sometimes you need to lower the fuel tank a few inches to gain access to these hoses. On some models, you'll need a fuel disconnect line tool to separate the fuel hoses.

Before disconnecting any hoses or lines, you may want to tag them so that you have a proper reference when reconnecting everything again. You can use masking tape for this.

Disconnect the electrical connector from the tank. This connector powers the fuel pump inside the tank. Look out for those fragile locking tabs that hold the connector in place.

After disconnecting the fuel lines and unplugging the electrical connector from the tank, drop the fuel tank. Cover any hoses you disconnected with a piece of clean plastic and secure it with a rubber band to prevent contamination. Depending on your particular model, you may not have to actually remove the tank out of the vehicle. Check to see if you can lower the tank just enough to remove the fuel pump or fuel sending unit assembly.

How to remove the fuel pump

Removing a fuel pump is a messy job, so ensure you are dressed appropriately and have good ventilation in your workspace. It is also important to note that you will be working around fuel and fuel vapors, so do not smoke, use an open flame, or do anything that may cause sparks or present a safety hazard.

• Disconnect the negative battery cable.
• Disconnect the fuel tank hose at the fuel pump and plug the hose with a bolt or wooden dowel to prevent fuel from flowing out. Also, disconnect the vapor-return hose if your vehicle has one. Make sure to wipe up any spilled fuel.
• Examine the old fuel hose. If it is frayed or cracked, replace it with a new fuel line hose.
• Disconnect the outlet line to the carburetor. Use a wrench on the fuel pump fitting and another on the line nut.
• Remove the two attaching bolts and extract the old fuel pump. Clean off any old gasket material from the mounting surface of the engine using a shop rag or plastic scraper.
• If your vehicle has an access door to the fuel pump, you will need to unplug the electrical connector and use a ratchet with an extension and a socket to remove the bolts holding the door in place. Keep the door bolts in a safe place and remove the door.
• If your vehicle does not have an access door, you will need to raise the vehicle and secure it on jack stands. Block each front wheel with a wooden block to prevent the vehicle from rolling.
• Place a floor jack under the fuel tank to support it and raise it slightly.
• Remove the bolts from the fuel tank holding straps or mounting screws. You may need to use a ratchet with a long extension and a swivel joint to reach the bolts.
• Disconnect the fuel filling hose or fuel lines from the fuel tank. You may need to lower the fuel tank slightly to access these hoses, and some models may require a fuel disconnect line tool.
• Before disconnecting the hoses or lines, tag them with masking tape for proper reference when reconnecting.
• Disconnect the electrical connector from the tank. This powers the fuel pump, so be careful with the fragile locking tabs.
• Once everything is disconnected, carefully drop the fuel tank. Cover any disconnected hoses with clean plastic and secure them with a rubber band to prevent contamination.
• Clean the top of the fuel tank, especially the top bracket of the fuel pump assembly, to prevent contaminating the tank with dirt and foreign matter after removing the module.
• To remove the fuel sending unit assembly, unscrew the cam lock ring securing the assembly to the tank. Use a brass punch or wooden dowel to avoid creating sparks that could ignite fuel fumes. Alternatively, use a screwdriver with a shop rag between the screwdriver and the lock ring tabs. Rotate the lock ring counterclockwise to release it. On some vehicles, screws hold the fuel pump module in place, so you will need to unscrew the bolts to remove the module.
• After removing the cam lock ring, slowly lift the fuel pump sending unit assembly out of the tank.
• Make sure to remove the seal (rubber ring) from the opening of the fuel tank and replace it with a new one.

Now that the fuel pump has been removed, you can inspect it and determine if it needs to be repaired or replaced. Remember to exercise caution and follow safety protocols when working with fuel systems.

How to install the fuel pump

Once you have the fuel pump assembly out of the fuel tank, place it on a workbench or suitable working space so that you can install the new pump in the assembly, unless you are replacing the whole unit.

Examine the electrical wiring, hoses, and overall condition of the assembly. If necessary, replace the assembly; otherwise, it may affect the operation of your new pump, and you'll need to redo the job in the near future.

Detach the fuel pump by disconnecting the bottom bracket, fuel pump strainer, electrical wires, and fuel outlet hose from the pump.

Install the new fuel pump in the assembly, and reconnect the wires, hoses, new pump strainer, and bracket.

Clean the inside of the tank with pressurized water to remove dirt and let it dry thoroughly before reinstalling the new fuel pump assembly.

Clean the fuel tank opening with carburetor cleaner before positioning the O-ring or rubber seal.

Install the assembly with the new fuel pump in the tank along with a bracket-assembly seal gasket. You may want to apply a thin layer of petroleum jelly to the bottom of the rubber seal to hold it in place as you lock the sending unit onto the tank.

With the pump module in place, lock the cam ring by rotating the ring clockwise using a brass chisel or screwdriver and hammer (or bolt the unit in place).

Then, use the floor jack to lift the fuel tank just enough to reconnect the fuel lines, pump sending unit electrical connector, and filler neck to the tank.

Carefully lift the fuel tank into position, making sure not to squeeze or damage the fuel lines and electrical connectors.

Secure the tank by attaching the tank straps or flange mounting bolts.

With the fuel tank in place and all hoses and electrical connectors plugged in, lower the vehicle, if you had to raise it. Or reinstall the access door.

Connect the negative cable to the battery.

Start the vehicle and check for leaks.

If you have not changed the fuel filter in more than a year, this is a good time to install a new one. That way, your new pump will have a clear path to fuel the engine.

Refill the tank with enough gasoline to cover the fuel pump—usually a quarter of a tank full.

Replacing an Inline Fuel Pump

Replacing an inline (external) fuel pump is much easier than installing an in-tank fuel pump because you don't have to drop or gain access to the fuel tank.

In some vehicle models, you'll find the inline pump inside the engine compartment; in others, it is near the fuel tank. In the latter case, you will still have to raise the vehicle and safely support it on jack stands. If you don't know where to find the external pump in your vehicle, consult your car owner's manual or repair manual for your particular vehicle model.

Place a container under the pump to catch the residual fuel in the lines.

Use a regular wrench to hold the fuel pump fitting while using a line wrench to disconnect the fuel line from the fuel pump. Make sure to use a line wrench (aka flare wrench); if you damage the line nut, you'll need to replace the whole line.

Disconnect the fuel line on the other side of the fuel pump.

Unscrew the bolt holding the pump mounting bracket in place.

Remove the old fuel pump.

Remove any gasket material from the pump mounting surface using a plastic scraper to prevent damaging the surface.

Apply a thin layer of gasket sealer to the new fuel pump gasket and place the new gasket in position.

Position the new fuel pump in place and secure it with the pump bracket.

Start connecting the two fuel lines to the pump by hand first.

Hold the pump fitting with a regular wrench and tighten the line with the flare wrench.

Tighten the other fuel line.

How to drain a fuel tank without removing it

Draining a fuel tank is a necessary step when replacing an in-line fuel pump. Here is a step-by-step guide on how to drain a fuel tank without removing it:

Before beginning, ensure you have the necessary tools and safety equipment, including eye protection, gloves, and a fire extinguisher nearby. It is also important to work in a well-ventilated area to prevent the buildup of flammable fumes.

Locate the fuel pump relay in your car's fuse box. The fuse box is usually located in the engine compartment or near the steering wheel. Once located, remove the relay to cut power to the fuel pump, preventing any accidental activation during the draining process.

Next, locate the fuel tank and find the fuel lines connected to the pump. You will need to disconnect these lines from the pump, placing a container beneath the lines to catch the drained fuel. Ensure that the container is approved for fuel storage and large enough to hold the amount of fuel in your tank. You may need to raise the vehicle and support it on jack stands for better access to the fuel tank and lines, especially if your car has a low-hanging exhaust or other components blocking access.

Clamping the fuel lines with suitable hose clamps can prevent fuel spillage and minimize the risk of fire. Once the clamps are securely in place, you can carefully disconnect the lines from the pump. Now, you can begin to drain the fuel tank. Loosen the drain plug on the fuel tank using a suitable wrench, allowing the fuel to flow into the container. Make sure that the container is properly secured and cannot tip over during the draining process.

Once the fuel has finished draining, you can tighten the drain plug securely. Reattach the fuel lines to the pump, ensuring that the connections are tight to prevent leaks. Finally, reinsert the fuel pump relay, and you can proceed with replacing the in-line fuel pump. Always properly dispose of the drained fuel at an authorized facility, and never leave it unattended or in an unsafe location.

By following these steps, you can safely and effectively drain your fuel tank without the need to remove it from your vehicle, making the process of replacing an in-line fuel pump more accessible and efficient. Remember always to prioritize safety when working with flammable liquids and vehicle systems.

How to prep and install a new fuel pump

Before installing a new fuel pump, you must first identify the problem with your current fuel pump. Common issues include a no-start, a noisy pump, or a faulty fuel gauge. Once you have identified the issue, you can proceed with the necessary repairs or replacement.

If you are experiencing a no-start problem, go to a quiet place and switch the key on without starting the engine. Listen for the fuel pump to run for a few seconds. If you hear the pump running, the next step is to check the pressure and fuel quality.

Now, it's time to prep and install a new fuel pump. Here's a step-by-step guide:

• Park your vehicle on a flat surface, away from traffic. The ideal location would be a garage, an empty parking lot, or a level driveway.
• Relieve the fuel system pressure and disconnect the negative battery cable. If the fuel pump hasn't been running, there won't be any pressure.
• Siphon fuel from the tank, especially if there is a significant amount of fuel remaining. This step may require special procedures for vehicles with anti-siphon nets in the filler tube.
• Disconnect the filler tube hose, the EVAP system connections, and the wires and fuel line connections from the pump.
• Lower the tank and disconnect the fuel lines to remove the old fuel pump.
• Install the new fuel pump with a new gasket or o-ring. Ensure that the outlet of the new pump is pointing towards the engine.
• Reinstall the fuel tank and reconnect all the disconnected components, including the negative battery cable.
• Fill the tank with good-quality fuel and test your vehicle to ensure the new fuel pump is functioning correctly.

It is important to note that fuel pump installation is a complex process, and it is recommended to hire a professional or seek guidance from a certified technician. Additionally, make sure to compare your new fuel pump with the old one to ensure they match, and always use the correct fittings and thread sealant to avoid leaks.

Frequently asked questions