Replacing The Fuel Pump On A Chevy 305 Engine

If you're looking to replace the fuel pump on your 1980 Chevy 305 engine, you've got a task ahead of you. While it's possible to do this with the engine still in the car, it's much easier if the engine has already been removed. You'll need to decide whether to replace the mechanical pump with an electric one, or to put an electric pump in by the tank and keep the mechanical pump as a backup. You'll also need to be careful not to damage any other parts of the engine while you're working.

The fuel pump is located on the passenger side front corner of the engine

To replace the fuel pump, you will need to remove the metal fuel line. Wrap a rag around the flare nut to capture any leaking fuel. Do not bend the metal line. Remove the rubber fuel line from the pump and plug the line to prevent any fuel leaking. Remove the fuel pump flange bolts. You will then need to remove the fuel pump backing plate to access the fuel pump push rod.

When installing the new fuel pump, clean the parts and lightly coat the push rod with grease. This will prevent the push rod from falling out. Insert the push rod into the hole until it contacts the cam shaft. Clean the engine block and the fuel pump backing plate, gluing a new gasket to the back of the plate. Place the plate in position and start the bolts in their holes. Put the fuel pump in place, holding it upright and starting the threads on the bolts. Tighten the bolts to approximately 25 ft/lbs. Replace the rubber fuel lines and start the flare nut by hand. You may need to wiggle the metal line to get the threads to start.

Use a 5/8 line wrench to remove the metal fuel line

To remove the metal fuel line from your 1980 Chevy 305 engine, you will need a 5/8" line wrench. This is the tool required to remove the flare nut that holds the metal fuel line in place.

Before you begin, it is important to note that if the engine has been running recently, the fuel line may be pressurized with fuel. This means that you need to be prepared for fuel to leak when you remove the flare nut. Wrap a rag around the wrench and flare nut to capture any leaking fuel. Ensure that you do not smoke while performing this task, and confirm that no one else in the vicinity is welding or using a nearby flame.

Now, use the 5/8" line wrench to loosen and remove the flare nut. Once the flare nut is removed, slide it back and then remove the metal fuel line from the fuel pump fitting. It is important not to force the metal line out of the fitting, as this could cause it to bend. Bending the metal line will make it difficult to start the threads when you are ready to reinstall the new fuel pump.

After removing the metal fuel line, the next step is to remove the rubber fuel line from the pump. It is recommended to plug the fuel line with something, such as the butt end of a drill bit, to prevent fuel leakage. Additionally, check the valves in the fuel pump to ensure that no fuel drains onto the floor.

Remove the rubber fuel line from the pump

To remove the rubber fuel line from the pump, you will need to be cautious and prepared. The rubber fuel line is attached to the fuel pump inlet with a small clamp. Firstly, locate the small clamp and have a suitable tool ready to loosen it. A line wrench is often used for this task, but the specific size of the wrench will depend on the model of your Chevy 305 engine. For most classic Chevy small block fuel pumps, a 1/2" line wrench is used.

Before loosening the clamp, be aware that if the engine has been running recently, the fuel line may be pressurized with fuel. Wrap a rag around the wrench and flare nut to capture any leaking fuel. Ensure that no one is smoking or using a naked flame nearby. Once you have taken these safety precautions, carefully loosen the clamp with your wrench.

Now that the clamp has been loosened, you can proceed to remove the rubber fuel line from the pump. Gently pull the rubber fuel line away from the pump, being careful not to spill any fuel. Once the line is free, plug the end of the line with something to prevent further leakage. A useful item for this purpose is the butt end of a drill bit.

At this point, you may also want to consider replacing the rubber fuel line with a new one, especially if the existing line is worn or damaged. This will help ensure the safety and reliability of your fuel system.

Use a socket, ratchet and extension to remove the fuel pump flange bolts

To remove the fuel pump flange bolts, you will need a socket, ratchet and extension. The bolts on the fuel pump are typically 7/16", but it is not uncommon for them to be replaced with bolts featuring a 9/16" head. The bolt size is a 3/8" course thread.

When removing the bolts, it is important not to remove them entirely one at a time. Instead, loosen both bolts and then alternate between them until they are both out. This will ensure that you do not encounter any difficulties when removing the bolts.

By using the correct tools and following this process, you will be able to successfully remove the fuel pump flange bolts on your 1980 Chevy 305 engine.

Install a new fuel pump

The first step is to decide what to do with the old mechanical pump. You have two options:

• Leave the mechanical pump in place and put an electric one by the tank. This is a good option if you want a backup in case the electric fuel pump fails.
• Remove the mechanical pump and replace it with an electric pump. This is a simpler option, as you can upgrade your entire fuel pump system in one go.

Removal and replacement process

First, uninstall the mechanical fuel pump. Then, cover the hole with a block-off plate gasket and sealer.

Next, mount the new electric fuel pump near the gas tank and connect it to the fuel line. Install a filter next to the electric fuel pump, and wire the pump to the ignition switch.

Tips for installing a new fuel pump

• Use a suitable replacement. For example, Edelbrock mechanical fuel pumps are made in the USA.
• Use a new backing plate gasket and a strong adhesive to hold the gaskets in place during assembly.
• Use knurled Allen head bolts for the two bolts holding the pump to the plate/engine. This makes it easier to tighten the bolts.
• Use a magnet or a hacksaw blade to hold up the pushrod while you install the new pump.
• Grease can also be used to hold the pushrod in place, but this may not work in hot climates.
• If you are installing an electric fuel pump, mount it close to the gas tank, away from heat sources, and not in an enclosed area.

Frequently asked questions