Replacing Lawnmower Fuel Pumps: A Step-By-Step Guide

The fuel pump is an essential component of a lawnmower. It pumps fuel from the gas tank to the carburettor, which powers the lawnmower. If the fuel pump is damaged, it is impossible to use the lawnmower safely, so repair or replacement is essential. This can be done in less than two hours by locating the pump, testing it, inspecting it, reassembling the pump parts, and performing a final test.

Locating the pump

Locating the fuel pump on your lawnmower is the first step to fixing it. The fuel pump is an essential component of the machine, so it's important to be able to find it. It pumps fuel from the gas tank to the carburetor, which powers the lawnmower.

The best way to locate the fuel pump on your lawnmower is to refer to the owner's manual. There should be a diagram that shows where all the parts are located. Typically, the fuel pump is found mounted on the carburetor, near the fuel tank, or between the tank and the carburetor. It will be connected to the tank and the carburetor by rubber gas tubes.

If you are still having trouble locating the fuel pump, it may be helpful to know that it is usually a small, round pump with either a plastic or metal body. It is also worth noting that some lawnmowers do not have a fuel pump and are instead gravity-fed systems.

If you are still unable to locate the fuel pump, you can try following the fuel line from the tank to the carburetor, as the pump should be located somewhere along this path. Additionally, you can try checking for the crankcase vent, as the fuel pump hose usually connects to this.

Testing the pump

Before assuming that your mower's fuel pump is defective, you should perform a quick test. Start by disconnecting the fuel line from where it is connected to the mower's carburetor. Then, turn on the power supply and check to see if gas is spurting from the fuel line. If it is not, the problem is most likely in your fuel pump.

If you suspect the issue lies with the fuel pump, you will need to remove it from the mower using a wrench, pliers, and a screwdriver. Once the pump is removed, carefully disassemble it by removing the screws that hold its parts together. Be careful not to damage any seals or gaskets during this process.

After disassembling the pump, inspect its internal components for any signs of damage or foreign matter such as sand or gasoline resin deposits. If you notice any deposits, spray the surfaces with a resin solvent, let it sit for about 10 minutes, and then wipe it clean with a cloth. Use a small, soft brush or cloth to remove any particles of sand or debris.

Finally, put the pump parts back together, replacing any gaskets or seals that may have become detached or damaged during the process. Reattach the pump to the mower, connecting all the electrical wires and fuel lines except for the one between the pump and carburetor.

Now, you can perform the final test. Repeat the same procedure as before by turning on the pump's power supply and observing if fuel is being pumped out of the detached fuel line. If so, your repair was successful. Reattach the fuel line and start your mower to ensure it is functioning properly.

Inspecting the pump

Step 1: Remove the Pump

Use a screwdriver, wrench, or pliers to carefully remove the fuel pump from the lawnmower. This step may vary depending on the model of your lawnmower, but generally, you will need to loosen the mounting screws and carefully lift the pump out of its housing. Make sure to disconnect any attached hoses or wires before attempting to remove the pump.

Step 2: Disassemble the Pump

Once the pump is removed, carefully disassemble it by unscrewing the parts that hold it together. Be cautious not to damage any seals or gaskets during this process. It is important to keep the disassembly process organised, as you will need to reassemble the pump later.

Step 3: Inspect for Damage

With the pump disassembled, carefully examine each component for any signs of damage, wear, or tear. Look for broken, bent, or damaged parts. Common issues include hairline cracks, softening, or hardening of the pump body or hoses. Additionally, check for any foreign matter, such as sand, debris, or gasoline resin deposits, which could be causing operational issues.

Step 4: Clean the Pump

If you notice any resin deposits, which often appear as brownish discolouration, use a resin solvent to spray the affected surfaces. Allow the solvent to sit for about 10 minutes to dissolve the resin effectively. Then, use a clean cloth to wipe away the dissolved resin. For any remaining particles or debris, use a small, soft brush or cloth to gently remove them. Soak metal parts in an all-purpose parts cleaner for up to 15 minutes to ensure a thorough cleaning.

Step 5: Assess the Hoses

Pay close attention to the condition of the hoses. Check for any cracks, softening, or hardening of the hose material. If the hoses show any signs of deterioration, it is important to replace them with new ones. Ensure that you purchase replacement hoses that are compatible with your specific lawnmower model.

Step 6: Replace Worn or Damaged Parts

If, during your inspection, you find any worn or damaged parts, such as gaskets, diaphragms, seals, or springs, make sure to replace them with original manufacturer's repair kit parts. It is crucial to use parts sourced directly from the manufacturer or authorised dealers to ensure compatibility and maintain the performance of your lawnmower.

Remember, safety should always be a priority when working with power equipment. Refer to your lawnmower's user manual for specific safety instructions and guidelines. Additionally, it is recommended to wear appropriate protective gear, such as gloves and eye protection, during the inspection and repair process.

Reassembling the pump parts

Once you have thoroughly inspected the pump and its parts, you can begin reassembling the pump. This process involves putting the pump parts back together, making sure to replace any gaskets or seals that became detached or damaged during disassembly. It is important to handle the pump parts with care to avoid causing any further damage.

Firstly, place the diaphragm spring and the cup over the center of the pump chamber. Insert a valve spring as well. Then, install the diaphragm, gasket, and cover, securing them in place with the pump screws. Make sure to tighten the screws securely using a torque wrench.

Next, attach the pump to the carburetor or mounting bracket using the pump mounting screws. Refer to the owner's manual or a diagram to ensure you are attaching the pump to the correct location. If your pump is electric, reconnect the electrical wires.

Finally, reconnect all the fuel lines, except for the one between the pump and the carburetor. Once you have reassembled the pump and secured it in place, you can proceed to test the pump to ensure it is functioning properly.

The final test

Now that you've replaced the fuel pump, it's time for the final test to ensure that your lawnmower is working correctly. This test is similar to the initial test you performed to diagnose the issue with your fuel pump.

First, locate the fuel line that connects to the mower's carburetor and disconnect it. Ensure that the fuel pump's power supply is turned on, and then check to see if gas is spurting from the fuel line. If you can see fuel being pumped out of the detached fuel line, your repair has been successful.

Finally, reconnect the fuel line that you used for testing, and start your lawnmower. Your mower should now be running smoothly, thanks to the new fuel pump.

It's important to note that if your fuel pump was damaged beyond repair and you had to replace it entirely, you should refer to your lawnmower manufacturer's instructions for any additional steps or precautions. Additionally, always make sure to wear protective gear and exercise caution when working with power tools and flammable substances.

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