Replacing A Fuel Pump In A 1990 F150: Step-By-Step Guide

If you're looking to replace the fuel pump on your 1990 F150, you're in for a bit of work. The fuel pumps on these trucks are located inside the fuel tanks, so you'll need to remove the bed or drop the tank to access it. It's recommended to have as little fuel in the tank as possible to minimize weight when doing this job. Once you have access to the tank, the process of replacing the fuel pump is relatively straightforward. You can find fuel pump modules online or at auto parts stores, and they typically come with the necessary components for replacement. Be sure to clean the cover and inside and outside of the tank, and replace the old strainer and fuel pipe. Additionally, it's important to address any underlying issues that may have caused the fuel pump to fail, such as a clogged filter.

Disconnect the battery and drop the bolts holding the bed to the frame

To replace the fuel pump on your 1990 F150, you'll need to disconnect the battery and drop the bolts holding the bed to the frame. Here's a step-by-step guide to help you through the process:

Disconnect the Battery

• Locate the battery in your F150. It is usually found in the engine bay, near the firewall, or under the hood.
• Identify the negative (-) and positive (+) terminals.
• Disconnect the negative terminal first. Use an appropriate-sized wrench or socket to loosen the terminal clamp and lift it off the battery post.
• Cover the terminal with electrical tape or a plastic bag to prevent accidental contact.
• Repeat the process for the positive terminal.

Drop the Bolts Holding the Bed to the Frame

• Identify the bolts holding the bed to the frame. These bolts are typically located along the perimeter of the bed, where it meets the frame.
• Apply penetrating oil to the bolts a few days before starting the project. This will help loosen any rust or corrosion.
• Using the appropriate socket or wrench, turn the nuts underneath the bolts counterclockwise to loosen them.
• If the bolts are frozen or difficult to turn, consider using an impact wrench or breaker bar for more force.
• In case the bolt heads break or spin, you can use a dremel tool or cutting wheel to cut through them. Alternatively, you can tack weld a piece of flat bar to the bolt heads to gain more leverage.
• With most bolts loosened, carefully lift and remove the bed from the frame. You may need assistance from another person to lift and support the bed.

Remember to work with safety in mind. Wear appropriate protective gear, such as gloves and eye protection, and ensure proper ventilation if working in an enclosed space.

Disconnect the fuel filler hose

Disconnecting the fuel filler hose on a 1990 F150 is a delicate process, but it can be done with the right tools and knowledge. Here is a step-by-step guide on how to do it:

Step 1: Remove the filler hose

Locate the filler hose inside the fuel door and remove the three screws around the filler orifice. This will allow you to access the hose and start the detachment process.

Step 2: Loosen the clamps

Under the truck, you will find two clamps that hold the filler hose in place. Loosen the right clamp first and then the left one. Slide the clamps off the mounting ear to free the filler hose.

Step 3: Pull the filler hose

Now, pull the filler hose away from the filler body. There is a nylon pipe inside the filler body that extends into the tank, so you will need to flex and pull gently to remove it completely.

Step 4: Deal with the mounting straps

The filler hose is connected to the fuel tank by mounting straps. Use a box wrench and a socket to loosen the nuts at each end of the straps. You may need a breaker bar if the nuts are too tight.

Step 5: Lower the tank

As you start to drop the tank, you will notice that the filler hose holds the back of the tank up, causing the front to fall faster. This is normal and will give you better access to the connections at the sending unit.

Step 6: Disconnect the connections

At the sending unit, you will see the pressure and return lines, as well as an electrical connection. Carefully pry the tabs on the electrical connection to release it and pull it loose.

Step 7: Remove the fuel lines

The fuel lines are held in place by fittings and nylon clips. Use a small screwdriver to pry the clips out while pressing on the legs to release them. Again, wear safety glasses during this step as some fuel may leak out.

Step 8: Detach the vent hose

To remove the vent hose, use two large screwdrivers to pry it upwards. There is a rubber gasket at this connection that you will need for the new tank, so be sure to remove it carefully.

Step 9: Lower the tank further

Continue to lower the tank and remove the ratchet straps completely. You may need to use wood blocks to support the tank as you work.

Step 10: Finalise the process

With the tank now disconnected, lower it further while sliding the filler hose free of the chassis. Once the tank is out, loosen the hose clamp and carefully pry the filler hose off the inlet nipple.

It is important to work safely and carefully throughout this process, especially when dealing with fuel lines and connections. Take your time, use the proper tools, and always wear the necessary protective gear, including safety glasses.

Tilt the bed upward to access the tank

To tilt the bed upward to access the tank, start by dropping the bolts that hold the bed of your F150 to the frame. You should then disconnect the battery and the fuel filler hose.

Once this is done, you can tilt the bed upward and prop it up with a piece of wood, such as a 16" piece of 2x4. This will give you access to the top of the tank.

It is also possible to access the tank by removing it completely. To do this, ensure the tank is as empty as possible to minimise weight, then remove the filler hose, tank straps, and protective skidplate.

Remove the old fuel pump module and install the new one

To remove the old fuel pump module and install the new one, follow these steps:

First, make sure you have the necessary tools and safety equipment, including eye protection, gloves, and a jack or jack stands to safely lift and support the vehicle. It is also recommended to work on a flat, level surface to ensure stability.

Next, locate the fuel pump module. On a 1990 F-150, the fuel pump is located inside the fuel tank. To access it, you will need to remove the bed of the truck by unbolting it from the frame and disconnecting the fuel filler hose. Work with at least one other person to carefully lift and remove the bed, as it can be challenging to do so safely.

Once you have accessed the fuel tank, you will need to remove the old fuel pump module. This typically involves unbolting the module, disconnecting any wiring, and carefully removing it from the tank. Be sure to note the orientation of the fuel pump and fuel lines, as you will need to install the new one in the same way.

Before installing the new fuel pump module, take the time to clean the cover and inside of the tank, and replace the old strainer and fuel pipe. It is also recommended to replace the fuel tank gasket and the sock strainer that goes over the bottom of the fuel pump housing.

Finally, install the new fuel pump module. Ensure that you install it in the correct orientation, with the fuel lines connected properly. Secure the module in place with the appropriate bolts and reconnect any wiring.

Once the new fuel pump module is installed, you can lower the fuel tank back into place and reattach the bed of the truck. Be sure to tighten all bolts securely and reconnect the fuel filler hose.

With the new fuel pump module installed, you can now start the engine and check for any leaks. If there are no leaks, your new fuel pump should be working properly.

Replace the fuel tank gasket and sock strainer

To replace the fuel tank gasket and sock strainer on a 1990 F150, follow these steps:

Firstly, ensure that the fuel tank is mostly empty before beginning any work. This is important for safety reasons, as a full tank weighs about 35 pounds, with fuel weighing around 6 pounds per gallon. You can achieve this by siphoning the fuel or simply driving the truck until the tank is mostly empty.

Next, hit the four tank mounting nuts with a penetrating spray the night before you start the job. This will make it easier to remove them when you begin the replacement process.

Now, you can begin to remove the fuel tank. Put on safety glasses to protect your eyes from any fuel or debris. First, you will need to release the pressure in the fuel system. Do this by opening the Schrader valve on the fuel rail. Unscrew the cap, cover it with a rag, and then press the valve with a screwdriver or another pointed object.

The fuel tank has four hoses and an electrical connector attached to it. These will need to be carefully disconnected. At the sending unit, you will find the pressure and return hoses, as well as a four-wire electrical connector. The vent hose is located in the center of the tank, and the filler hose is on the driver's side.

To remove the filler hose, follow these steps:

• Remove the three screws around the filler orifice inside the fuel door.
• Under the truck, loosen the right clamp that mounts the filler to the chassis.
• Slide the clamp off the mounting ear.
• Loosen the left clamp and slide it up the filler body.
• Pull the filler away from the filler hose.

You will see a nylon pipe inside the filler body that extends into the tank through the filler hose. Flex and pull the filler body to remove it completely.

Now, break the nuts loose at each end of the mounting straps. Use a box wrench against the frame to hold the bolt head, and a socket to loosen the nuts. You can use a breaker bar if the nuts are stubborn.

At this point, you can lower the tank. There are two common methods: using a floor jack and a piece of plywood, or with motorcycle ratchet straps.

As you drop the tank, the filler hose will cause the back to be held up, so the front will fall faster. This is helpful, as the connections at the sending unit are disconnected next. Carefully pry the tabs to release them, and then pull the connector loose.

The fuel lines have fittings that are locked in place with nylon clips. To remove them, you will need to pry out the clips using a small screwdriver. The pressure line has a 3/8" fitting and a black clip, while the return line has a 5/16" fitting and a white clip. Remember to wear your safety glasses during this step, as some fuel may leak out.

Detach the vent hose fitting by prying it upwards with two large screwdrivers, one on each side. There is a rubber gasket at this connection that you will need to remove. You can do this now or after the tank is out.

Continue lowering the tank, adding and removing wood blocks as needed to position it. Once the tank is resting on the blocks, remove the ratchet straps completely.

Now, you can fully disconnect the tank. Lower it while sliding the filler hose free of the chassis. Once the tank is out, loosen the hose clamp and pry the filler hose off the inlet nipple.

To remove the locking ring, use a non-metal chisel or punch to avoid any risk of explosion. If the locking ring is damaged, you can simply pull it off.

Now, you can access the fuel pump assembly. Carefully remove the fuel delivery module, being cautious not to damage the suction screens and float. If it is difficult to remove in one piece, try removing the sending unit (float) first. This will give you more room to work.

At this point, you have access to the fuel tank gasket and sock strainer. Replace these components, following the instructions provided with the new parts. Ensure that they are securely fitted before reassembling the fuel tank and pump module.

Reassembly is the reverse of the removal process. Carefully reconnect all hoses and electrical connectors, ensuring that everything is securely fastened before moving on to the next step.

Finally, you can refill the fuel tank and start the engine to test your work. Ensure that there are no leaks and that the engine runs smoothly.

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