Replacing The Mechanical Fuel Pump In Your 350 Engine

Changing a mechanical fuel pump on a Chevy 350 engine is a fairly simple task that can be done at home in a couple of hours. It is a messy job, so it is important to be dressed appropriately and to have the right tools. The fuel pump is located on the passenger side front corner of the engine, in front of the motor mount. This step-by-step guide will walk you through the process of changing the mechanical fuel pump on your Chevy 350.

Characteristics of Changing a Mechanical Fuel Pump 350

Disconnect the negative battery cable

Disconnecting the negative battery cable is a crucial first step when replacing your mechanical fuel pump. This step is essential for your safety and to prevent accidental damage to your vehicle's electrical components.

Here's a step-by-step guide on how to safely disconnect the negative battery cable:

• Turn off your vehicle: Before beginning any repairs or maintenance, always ensure your vehicle is turned off. Attempting to work on a running engine can cause spikes in sensitive electronics, leading to potential damage.
• Locate the battery: The battery's location can vary depending on your vehicle. Most cars have it under the hood, while some models keep it in the trunk. If you're unsure, refer to your owner's manual for the exact location.
• Identify the battery terminals: The negative terminal is typically marked with a "-" symbol and connected to a black cable. The positive terminal, on the other hand, is marked with a "+" symbol and usually has a red plastic cover and a red cable.
• Loosen the nut on the negative terminal: Using a wrench, loosen the nut that secures the negative battery cable to the battery post. Be cautious not to let the cable fall back onto the terminal.
• Move the cable away from the terminal: Ensure that the negative cable is no longer touching the battery terminal. This step is crucial for safety reasons. If the cable accidentally touches the terminal while you're working, it could create a short circuit.
• Optional: Disconnect the positive terminal: While it's not necessary to remove both cables, doing so can provide an extra layer of safety. If you choose to disconnect the positive terminal as well, first ensure that the negative cable is securely moved away from the battery. Then, use your wrench to loosen the nut on the positive terminal and remove the cable.

By following these steps, you'll have successfully disconnected the negative battery cable, which is the first step in changing your mechanical fuel pump. Remember to work in a well-ventilated area and take the necessary precautions when handling fuel and fuel vapors.

Remove the old fuel pump

To remove the old fuel pump, start by disconnecting the negative battery cable. Next, 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. If your vehicle has one, also disconnect the vapor-return hose. Be sure to wipe up any spilled gas.

Now, disconnect the outlet line to the carburetor. To do this, use a wrench on the fuel pump fitting and another on the line nut. With the hoses disconnected, you can now remove the fuel pump itself. Start by removing the two attaching bolts. As you do this, be careful not to bend the metal line. Once the bolts are removed, extract the old fuel pump.

Before installing the new fuel pump, clean off any old gasket material from the mounting surface of the engine using a shop rag.

Prep and install the new fuel pump

Before you begin, ensure you are dressed appropriately and that your workspace is well-ventilated. It is also important to note that you should not smoke, use an open flame, or do anything that may cause sparks or present a safety hazard.

First, apply a coat of gasket sealer to both sides of the new gasket. Next, put the attaching bolts through the new pump and slip the gasket over the bolts. Make sure the push rod is correctly installed in both the engine and the fuel pump. If the push rod slides out, you can pack it with heavy grease to hold it in place while you install the pump.

Now, install the new pump on the engine. Attach the fuel outlet line that runs to the carburetor. If it's difficult to connect, remove the other end of the line from the carburetor. Connect the line to the fuel pump, and then reattach the other end to the carburetor. Use a wrench to hold the fuel pump fitting and tighten the line nut with another wrench.

Attach the fuel inlet hose from the gas tank and the vapor-return hose. Tighten all clamps. Make sure all fittings, hoses, and clamps are tight and that there are no leaks.

Finally, reconnect the battery ground cable, start the vehicle, and check for leaks. Once you've inspected your work and ensured it's free of leaks, your vehicle is good to go.

Reattach the fuel outlet line

Reattaching the fuel outlet line is a crucial step in the process of changing a mechanical fuel pump. Here is a detailed, step-by-step guide on how to do it:

Before beginning, ensure that you have already disconnected the negative battery cable, disconnected the fuel tank hose at the fuel pump, plugged the hose with a bolt or dowel, disconnected the vapor-return hose (if applicable), and wiped up any spilled fuel. Additionally, make sure you are wearing appropriate clothing for this messy job and that your workspace is well-ventilated and free of any open flames or sparks.

Now, to reattach the fuel outlet line:

• Take the fuel outlet line that runs to the carburetor and connect it to the new fuel pump. If you find it difficult to connect, you can try removing the other end of the line from the carburetor first.
• Use a wrench to hold the fuel pump fitting securely.
• With another wrench, tighten the line nut onto the fuel pump. Ensure that the line is securely attached to the fuel pump.
• Proceed to attach the fuel inlet hose, which is connected to the gas tank, and the vapor-return hose (if your vehicle has one).
• Tighten all the clamps to secure the hoses in place.
• Reconnect the negative battery cable.
• Start the vehicle and carefully check for any leaks around the fuel pump and hoses. Ensure that your work area remains well-ventilated during this step.

By following these steps, you can securely reattach the fuel outlet line when changing a mechanical fuel pump. Remember to take appropriate safety precautions when working with fuel and fuel vapors.

Reconnect the battery cable

After you've installed the new mechanical fuel pump, it's time to reconnect the battery cable. This is a crucial step, as it will provide power to the fuel pump and other electrical components in your vehicle. Here's a detailed guide on how to do it:

Prepare the Workspace:

Before reconnecting the battery cable, ensure your workspace is clean and free of any tools or debris. It's important to work safely, especially when dealing with electrical systems. Clear any tools or parts that may have been used during the fuel pump replacement.

Locate the Battery:

Find the battery in your vehicle's engine compartment. It is typically located in an easily accessible area. The battery will be secured in place with a clamp or bracket.

Identify the Battery Cable:

Identify the battery cable that needs to be reconnected. You will be reconnecting the negative (ground) cable, which was disconnected earlier. The negative cable is usually black and has a "-" symbol or a black clamp.

Now, carefully reconnect the negative battery cable to the negative terminal on the battery. Ensure that the connection is secure and tight. Use a wrench or pliers if necessary to tighten the clamp, but be careful not to over-tighten it.

Inspect the Connection:

Once the cable is reconnected, inspect the connection to ensure it is secure and proper. Make sure the cable is firmly attached to the battery terminal and cannot be easily pulled off. A loose connection can cause electrical issues and affect the performance of your vehicle.

Start the Vehicle:

After reconnecting the battery cable, you can start the vehicle. Turn the key in the ignition and start the engine. With the battery reconnected, the fuel pump will now have power, and the vehicle should start normally.

Check for Leaks:

With the vehicle running, carefully inspect the fuel pump and its connections for any signs of leaks. This is an important step to ensure that your work is secure and there are no fuel leaks, which can be dangerous.

By following these steps, you can safely and effectively reconnect the battery cable after changing the mechanical fuel pump in your vehicle. Remember always to work with safety in mind and refer to a professional mechanic if you have any doubts or concerns.

Frequently asked questions