Replacing Fuel Pumps In Small Block Chevys: A Step-By-Step Guide

If you're looking to replace the fuel pump on a small block Chevy engine, you'll find it on the passenger side front corner of the engine, in front of the motor mount. While the specific process may vary slightly depending on the model year of your Chevy, the basic steps involve removing the fuel lines and pump flange bolts, taking out the old pump, and installing a new one with appropriate fittings and assembly. It's important to be cautious when handling fuel lines to prevent leaks and ensure safety.

The fuel pump's location

The fuel pump on a Chevy small block engine is located on the passenger side front corner of the engine, immediately in front of the motor mount. The fuel pump arm on the backside of the fuel pump is driven by a push rod, which is controlled by a camshaft lobe.

To access the fuel pump, you will need to remove the metal fuel line. This is done with a 5/8" line wrench. Be prepared for fuel to leak, so wrap a rag around the wrench and flare nut to catch it. Do not smoke and ensure no one is welding or using a flame nearby.

Once the flare nut is removed, slide it back but do not pull the metal line out of the fuel pump fitting. If you force it, it may bend and you will have difficulty starting the threads when reinstalling the new fuel pump.

Removing the metal fuel line

To remove the metal fuel line of a small block Chevy engine, you will need a 5/8" "line" wrench. On most classic Chevy small block fuel pumps, the wrench you use to remove the flare nut would be 1/2".

If the engine has been running recently, the fuel line will be pressurized with fuel. Wrap a rag around the wrench and flare nut to capture any leaking fuel. Be careful not to smoke, and ensure no one nearby is welding or using a flame.

Do not bend the metal line, even slightly. Once the flare nut is removed, slide it back, but do not pull the metal line out of the fuel pump fitting. If you force it, the metal line could bend, and it will be difficult to start the threads when it is time to reinstall the new fuel pump.

Remove the rubber fuel line from the pump and plug the fuel line to prevent leaking. You can use the butt end of a drill bit for this. Check valves in the fuel pump should prevent the fuel pump from draining fuel onto the floor. The fuel supply line can be 5/16" or 3/8".

Removing the rubber fuel line

To remove the rubber fuel line from a small block Chevy engine, you will need to first locate the fuel pump. The fuel pump on a small block Chevy is located on the passenger side front corner of the engine, in front of the motor mount.

Once you have located the fuel pump, you can begin the process of removing the rubber fuel line. Start by using a 5/8" line wrench to loosen the metal fuel line connected to the fuel pump. Be prepared for potential fuel leakage and take the necessary precautions, such as wrapping a rag around the wrench and flare nut to catch any leaking fuel. Do not smoke, and ensure no one is welding or using an open flame nearby.

After loosening the metal fuel line, you can now focus on the rubber fuel line. Disconnect the rubber fuel line from the pump. It is important to plug the fuel line to prevent leakage. You can use the butt end of a drill bit or a similar object to block the opening.

With the rubber fuel line disconnected and plugged, you can now proceed with the rest of the fuel pump replacement process. Remember to clean any residual grease or gasket material from the engine block and apply a new gasket and sealant as needed during the reassembly process.

When you are ready to reinstall the rubber fuel line, ensure that the metal fuel line is properly aligned with the fuel pump fitting. Start the flare nut by hand, and you may need to gently wiggle the metal line to get the threads to engage properly. Do not use a wrench at this point, as it can easily lead to cross-threading. There may be some tension in the fuel line, but avoid bending it. Flexing it slightly may be necessary to align it with the fuel pump fitting.

Removing the fuel pump flange bolts

To remove the fuel pump flange bolts of a small block Chevy engine, you will need a socket, ratchet, and extension. The bolts are typically 7/16", but it's not uncommon for them to be 9/16" if they have been replaced previously. The bolt size is a 3/8" course thread.

It is important to note that you should not remove one bolt entirely and then the other. Instead, loosen both bolts and then alternate between them until they are both out. This will ensure that you do not encounter any difficulties during the removal process.

Before beginning the removal process, be sure to have a rag handy to capture any leaking fuel. If the motor has been running recently, the fuel line may be pressurized with fuel. Do not smoke, and ensure that no one nearby is welding or using a flame.

Additionally, be careful not to bend the metal line, even slightly. Once the flare nut is removed, slide it back, but do not pull the metal line out of the fuel pump fitting. If you force it, the metal line may bend, and you will have difficulty starting the threads when it is time to reinstall the new fuel pump.

Once the fuel pump flange bolts are removed, you can proceed to the next step of removing the fuel pump backing plate.

Installing the new fuel pump

To install the new fuel pump, start by cleaning the parts and lightly coating the fuel pump push rod with a thick grease. This will prevent the push rod from falling out. Next, use a rag to wipe out the fuel pump push rod cavity, removing any excess oil. Insert the push rod into the hole until it contacts the cam shaft—do not force it with a hammer.

Clean any remaining gasket from the engine block and the fuel pump backing plate. Glue a new gasket to the back of the fuel pump backing plate using an adhesive like "yellow death" or weatherstripping. Ensure all parts are grease-free before gluing. Apply a thin smear of automotive silicone on the gasket surface.

Place the fuel pump backing plate on the engine block and start all four bolts in their respective holes. Tighten the two small bolts at the bottom of the plate, then remove the two fuel pump bolts. By starting all the bolts before tightening, you'll ensure proper alignment and avoid difficulty when installing the fuel pump flange bolts.

Glue the new gasket to the fuel pump itself, then apply a thin smear of automotive silicone to the gasket. Put the fuel pump bolts in the fuel pump flange bolt holes. Put a spot of grease on the end of the fuel pump arm and place the pump, holding it upright to prevent the fuel pump arm from slipping. Start the threads on each of the fuel pump bolts, alternating between them and tightening until snug. Tighten to approximately 25 ft/lbs. You should see a fine bead of silicone squeeze out from around the fuel pump and fuel pump backing plate.

Finally, 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. Push the fuel line straight into the pump fitting to centre it, making the flare nut easier to start. Do not use a wrench as you could cross-thread the fitting. There may be tension on the fuel line, but do not bend the line.

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