Replacing Sierra 18-7274 Marine Fuel Pump: Step-By-Step Guide

The Sierra 18-7274 Marine Fuel Pump is a replacement part for Mercruiser Stern Drive engines. It is designed to meet or exceed the original equipment specifications and fits various engine models, including MCM/MIE 898, 228, 250, 255, 260, and 280. The pump includes a mounting gasket and has specific fuel inlet and outlet positions. This fuel pump is available from several online retailers at different price points.

Sierra 18-7274 fuel pump compatibility

The Sierra 18-7274 Marine Fuel Pump is designed for use with MCM/MIE 898, 228, 250, 255, 260, and 280 engines. It is compatible with and interchangeable with several other fuel pump models, including the EMP 35-35274, GLM 77070, Mallory 9-35417, Mercruiser Stern Drive 71646, 78485, 86246, 86246A1, 86246T, and OMC Stern Drive 509409.

The Sierra 18-7274 fuel pump is designed to meet or exceed the specifications of the original equipment it replaces. It is a high-quality replacement part that is compatible with various watercraft applications and engine types.

The pump measures 10.5 x 6 x 4.25 inches and includes a mounting gasket. It is important to ensure that this fuel pump is the correct fit for your specific engine and application.

When considering the compatibility of the Sierra 18-7274 fuel pump, it is essential to refer to the specific engine and application requirements. This fuel pump is designed for marine use and is compatible with the Mercruiser Stern Drive and OMC Stern Drive engines, as mentioned earlier.

Additionally, the Sierra 18-7274 fuel pump is available from various sellers and distributors, ensuring accessibility and a range of purchasing options.

Removing the old pump

To remove the old Sierra 18-7274 marine fuel pump, you will need to locate the pump in the engine compartment. This fuel pump is designed for use with MCM/MIE 898, 228, 250, 255, 260, and 280 engines. It is interchangeable with parts from several other manufacturers, including Mercruiser, OMC, Carter, Mallory, and GLM.

Before beginning any work on your boat, make sure you have all the necessary tools and safety equipment. It is also important to consult the owner's manual or a marine mechanic for specific instructions and safety precautions.

Once you have located the fuel pump, the next step is to disconnect the fuel lines and electrical connections. Be sure to relieve the pressure in the fuel lines before disconnecting them to avoid spills and reduce the risk of fire. Place a rag or container under the connections to catch any fuel that may spill.

After disconnecting the fuel lines and electrical connections, you will need to remove the mounting hardware securing the fuel pump in place. This may involve removing bolts or other fasteners. Keep track of the order and orientation of the hardware to make reinstallation easier.

With the mounting hardware removed, you should now be able to carefully lift the old fuel pump out of its housing. Check the surrounding area for any debris or residue that may have accumulated and clean it if necessary. It is important to ensure that the area is clean and free of any debris before installing the new fuel pump.

Finally, inspect the old fuel pump for any signs of damage or wear. This can help you identify and address any underlying issues that may have contributed to the failure of the pump.

Installing the new pump

To install the new Sierra 18-7274 marine fuel pump, follow these steps:

Begin by locating the fuel pump on your engine. The pump's position can vary depending on the engine model, but it is usually located near the bottom of the fuel tank or close to the engine. Refer to your engine's manual or seek advice from a marine mechanic if you are unsure. Once you have located the pump, place a drain pan or container underneath it to catch any spilled fuel.

Proceed to disconnect the fuel lines from the pump. Be cautious as the fuel lines may be pressurized, and release the pressure slowly to avoid injury. You may need to use wrenches or other appropriate tools to loosen the connections. After disconnecting the lines, remove any electrical connections and mounting hardware securing the pump in place. Now, carefully lift out the old pump.

With the old pump removed, it's time to prepare the new Sierra 18-7274 fuel pump for installation. Ensure that you have the correct model for your engine, as different engines may require specific fuel pump configurations. Check that the new pump includes the necessary mounting gasket, and refer to the pump's instructions or your engine's manual to identify the correct flange ID and other relevant specifications.

Install the new pump by positioning it in the same location as the old pump. Secure the pump in place using the appropriate mounting hardware, ensuring that all connections are tight and secure. Reconnect the fuel lines and electrical connections, making sure that everything is properly aligned and attached.

Finally, before starting the engine, carefully inspect your work to ensure that all connections are secure and that there are no signs of fuel leaks. Refer to your engine's manual or consult a marine mechanic if you have any concerns or questions about the installation process. Once you have confirmed that everything is in order, start the engine and check for proper operation.

Testing the new pump

Once you have installed the new Sierra 18-7274 marine fuel pump, you will need to test it to ensure it is functioning correctly. Here is a step-by-step guide on how to do this:

Before starting the engine, it is important to perform a visual inspection of the new fuel pump to ensure it is securely mounted and that all connections are tight. Check for any signs of fuel leaks around the pump and confirm that the fuel lines are properly attached.

Next, you will need to prime the fuel pump. This process ensures that the pump is filled with fuel and any air is removed. Refer to your engine's manual for specific instructions on how to prime the fuel pump, as it may vary depending on your particular engine model. Priming typically involves manually pumping fuel through the system or running an electric primer pump.

Once the pump is primed, you can attempt to start the engine. With the engine off, turn the ignition key to the "On" position to activate the fuel pump. You should be able to hear the pump running for a few seconds as it pressurizes the fuel system. If you cannot hear the pump running, there may be an issue with the electrical connection or the pump itself.

Now, start the engine and let it run for a few minutes. Pay attention to the engine's performance and listen for any unusual noises. If the engine starts and runs smoothly, this is a good indication that the new fuel pump is working correctly.

Finally, you should check for fuel leaks again. With the engine running, inspect all the fuel lines, connections, and the pump itself for any signs of leaks. If no leaks are present and the engine is performing as expected, then you can be confident that the new Sierra 18-7274 marine fuel pump has been successfully installed and is functioning properly.

It is always a good idea to consult the engine's service manual or seek advice from a qualified marine mechanic if you are unsure about any aspect of the fuel pump replacement or testing process.

Maintaining the pump

Before Overhauling:

Clean the outer surface of the fuel pump to remove any dirt or grime buildup. This step is important as it ensures that no contaminants enter the pump during the maintenance process.

Disassembling the Pump:

• Clamp the fuel pump securely in a vice to stabilize it.
• Remove the delivery valve holder, which is responsible for holding the delivery valve in place.
• Take out the delivery valve, a crucial component for regulating fuel flow.
• Depress the plunger guide and remove the stop ring, which secures the plunger in place.
• Extract the plunger guide, which guides the plunger's movement.
• Remove the spring seats, spring, and plunger assembly, which work together to create the necessary pressure for fuel delivery.
• Take out the control sleeve and control rack, which are responsible for controlling the fuel pump's output.
• Unscrew and remove the barrel set screw, and then carefully take out the plunger barrel.

Cleaning the Components:

• Clean all the components with kerosene using a soft brush. Avoid using a steel brush to prevent scratching or damage to the parts.
• Pay special attention to the plunger and plunger barrel, as these should always be handled as a pair to ensure proper functioning.

Reassembling the Pump:

• Insert the plunger barrel and secure it in place with the set screws.
• Insert the control rack and fix the control sleeve, ensuring they are properly aligned.
• Match the marks on the control rack, control sleeve, and plunger. A mismatch of these marks can affect fuel delivery, so ensure they are correctly aligned.
• Assemble the spring seat, spring guide, and stop ring, following the reverse order of disassembly.
• Invert the pump and fix the delivery valve in place. If needed, replace the valve as a unit to ensure optimal performance.
• Apply molykote to the delivery valve and tighten the delivery valve holder to secure it in place.

Final Checks:

• After assembling the fuel pump, ensure that the control rack moves smoothly. This indicates that the rack is properly seated and functioning correctly.
• Check for any leaks or signs of damage. If everything appears to be in order, your Sierra 18-7274 marine fuel pump is now properly maintained and ready for use.

Frequently asked questions