Replacing A Fuel Pump: Step-By-Step Guide For Your Gas Tank

Replacing a fuel pump in a gas tank is a potentially dangerous but rewarding task to take on yourself. The fuel pump is located in the vehicle's gas tank and supplies pressurised gasoline to the fuel injectors in a car's engine. The pump is powered by a compact electric motor. A failing fuel pump will eventually stop working, causing the engine to stall or not start. Before you start, make sure you are working in a well-ventilated area and that you are wearing protective clothing and eyewear. It is also important to disconnect the battery and drain the fuel tank.

Safety precautions

Safety should be the top priority when replacing a fuel pump in a gas tank. Here are some detailed safety precautions to follow:

Prepare the Workspace

Before starting the replacement process, ensure you have a safe and accessible workspace. Work in a well-ventilated area, preferably outdoors, to minimize the risk of fire and inhaling harmful fumes. Keep the area free from any sources of sparks or flames, including cigarettes, light bulbs, and pilot lights. Have a fire extinguisher readily available in case of any accidents.

Wear Proper Safety Gear

Always wear protective clothing, such as safety goggles, gloves, and appropriate attire to shield yourself from fuel spills and splashes. Remember that gasoline is a highly flammable and dangerous substance, so take every precaution to avoid any contact with it.

Disconnect the Battery

It is crucial to disconnect the negative battery cable before proceeding. This helps prevent any accidental electrical discharges or sparks that could lead to an explosion or fire.

Relieve Fuel System Pressure

Before accessing the fuel system, relieve the fuel system pressure. This can be done by running the engine and pulling the fuel pump relay, or by pressing the Schrader valve on the pressure line momentarily to release the pressure.

Drain the Fuel Tank

If possible, drain or siphon out most of the fuel from the tank. This step significantly reduces the risk of spills and makes the fuel tank lighter and easier to handle during the replacement process.

Clean the Work Area

Keep the work area clean and free from dirt and debris. Before removing the fuel pump, clean the area around it to prevent any foreign objects from falling into the fuel tank. Additionally, clean the top of the tank and the mounting and seal surfaces using a shop towel and carburetor cleaner to ensure a proper seal when reassembling.

Use Approved Containers for Fuel

When draining fuel or storing it temporarily, always use approved containers, such as a gas caddy or gas can. Never use unapproved containers, as they may not be designed to handle flammable liquids safely.

Handle Fuel Vapors with Care

Fuel vapors are highly flammable and toxic. Be extremely cautious when working with fuel lines and vapor lines. Ensure that the work area is well-ventilated, and keep the vehicle's interior lights off to prevent any potential sources of ignition.

Avoid Electric Pumps

When removing fuel from the tank, use a hand siphon pump instead of an electric pump. Electric pumps pose a risk of creating sparks, which could lead to an explosion in the presence of flammable vapors.

Stay Alert and Patient

Replacing a fuel pump requires attention to detail and patience. Take your time during the process, and remain alert to avoid any mishaps. Ensure you have all the necessary parts and tools before starting to avoid any interruptions during the replacement.

Disconnecting the battery

First and foremost, safety should be the top priority when working with any electrical system in a vehicle. Ensure you are wearing the appropriate protective gear, including gloves and safety goggles, to safeguard yourself from any potential hazards.

Now, let's begin with disconnecting the battery. The first step is to locate the battery in your vehicle. It is usually located in the engine bay, near the front of the car. Once you have found the battery, identify the negative terminal. This is typically marked with a "-" symbol or a black cover. Using the appropriate size wrench or socket, loosen and remove the negative battery cable from the terminal. It is important to only disconnect the negative cable to avoid any arcing or short circuits. Set the cable aside, ensuring it does not touch any metal parts of the car.

At this point, the battery is disconnected, but it is essential to note that modern vehicles have complex electrical systems, and some components may still retain power even after disconnecting the battery. Exercise caution and avoid touching any exposed wires or electrical components.

If your vehicle has advanced electronic systems, it may be equipped with a backup power source or capacitor. In such cases, you will need to refer to the vehicle's service manual for specific instructions on discharging the capacitor or disconnecting the backup power source. This step is crucial to ensure that all electrical power is completely shut off before proceeding with the fuel pump replacement.

Once you have confirmed that all power is off, you can proceed with the next steps of replacing the fuel pump, such as relieving the fuel system pressure and removing the fuel tank. Remember to exercise caution and follow safety protocols throughout the entire process.

By following these instructions, you can safely disconnect the battery in your vehicle, ensuring a secure environment for you to work on the fuel pump replacement.

Draining the fuel tank

Before you start replacing the fuel pump, it is important to drain the fuel tank. This is because a full gas tank is heavy and can cause injury if it is dropped. Additionally, it is dangerous to work with a full tank of gas due to the risk of fire.

Some tanks come with a drain valve, which can be used to drain the fuel. Alternatively, you can use a hand siphon hose and a fuel-approved container to drain the tank. If your tank does not have a drain valve, you can remove the filler neck from the fuel tank to draw the fuel out.

To do this, remove the gas cap and insert a hard plastic line into the filler neck. Once the gas starts flowing, keep the fuel container below the level of the tank and have additional containers ready. You may also need to locate and remove the gas tank filler neck mounting bolts or remove the filler tube from the tank to aid in fuel removal.

It is important to work in a well-ventilated area when draining the fuel tank, as fuel vapors can be dangerous to breathe. Additionally, make sure that there are no sources of sparks or flames nearby, and do not smoke while working.

Once the tank is drained, you can proceed with removing the old fuel pump and installing the new one.

Removing the fuel lines and electrical connectors

Before removing the fuel lines and electrical connectors, it is important to relieve the fuel system pressure. This can be done by using a Schrader valve, removing the fuel pump fuse or relay, or unplugging the ignition coil electrical connector. Once the pressure has been relieved, the next steps can be followed:

First, disconnect the fuel outlet line going to the carburetor. This can be done by grasping the fuel pump fitting firmly with one wrench while unscrewing the nut with another wrench. Be prepared for some fuel to leak out at this point.

Next, locate the electrical connector for the fuel pump and fuel level sender. This will be in the same wiring harness. If access is difficult, wait until the tank is lowered slightly to undo the connector. Inspect the electrical connector for any burns or heated spots and replace it if necessary. A burned connector could cause the pump to fail.

Now, disconnect the fuel line using a fuel line removal tool. Again, fuel will leak, so be ready with a fluid catch basin. There will also be fuel vapour lines as part of the EVAP system that will need to be removed or disconnected.

At this point, double-check to ensure that all visible hoses and electrical connectors have been disconnected. Lower the tank and release any remaining top-mounted fuel lines or electrical connectors.

Finally, carefully remove the tank, exposing the fuel pump retainer ring. Use an aerosol cleaner to remove any dirt and debris from the area. This will keep the inside of the fuel tank clean while performing the repair.

Installing the new fuel pump

Now that you've removed the old fuel pump, it's time to install the new one. Here's a step-by-step guide on how to do this:

Firstly, you'll want to examine the fuel pump assembly and ensure it's in good condition. If there is any damage, replace the assembly. Then, detach the fuel pump by disconnecting the bottom bracket, fuel pump strainer, electrical wires, and fuel outlet hose from the pump.

Next, you can install the new fuel pump into the assembly. Reconnect the wires, hoses, new pump strainer, and bracket. If you're not replacing the whole unit, clean the inside of the tank with pressurized water to remove any dirt and let it dry thoroughly before reinstalling the new fuel pump assembly. Clean the fuel tank opening with carburetor cleaner and install the assembly with the new pump, 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 it clockwise using a brass chisel or screwdriver and hammer, or bolt the unit in place.

Now, 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, ensuring that you don't damage the fuel lines and electrical connectors. Secure the tank by attaching the tank straps or flange mounting bolts.

Finally, with the fuel tank in place and all hoses and electrical connectors plugged in, lower the vehicle if you had to raise it. Reconnect the negative cable to the battery and start the vehicle to check for leaks.

If you haven't changed the fuel filter in over a year, it's a good idea to install a new one at this point. You should also refill the tank with enough gasoline to cover the fuel pump—usually about a quarter of a tank full.

Frequently asked questions