Lawn Mower Repair and Blade Maintenance

DIY Lawnmower Maintenance and Repair

By Mark J. Donovan

When the lawn needs mowing for the first time of the season do you simply pour gasoline into the lawnmower’s gas tank and then yank on the pull cord to no avail? If this situation sounds like you, don’t worry. You represent the majority of homeowners when it comes to firing up the lawnmower for the first time of the season.

To avoid the frustration of a non-working lawnmower the best defense is a good offense. To ensure your lawnmower will start the first time, and every time when your lawn needs mowing, its wise to do some upfront lawnmower maintenance and repair. With an hour or two of your time you can ensure you lawnmower starts right up, runs smoothly and cuts grass like a hot knife through butter.

Summarized in the paragraphs below is a list of lawnmower maintenance and repair instructions that most homeowners can tackle on their own. Once going through this set of maintenance instructions your lawnmower should fire up and run like a fine oiled machine.

Check for Gasoline in the Gas Tank

First check to see if there is gas in the lawnmower. If you have old gas in the lawn mower and did not put in a fuel stabilizer into the gas tank at the end of the previous mowing season, I highly recommend replacing the gas. If you had drained the gas tank at the end of the previous mowing season, then fill the tank with fresh new gas.

Remove and clean the Spark Plug

A fouled spark plug is the root cause of most lawnmowers not starting, with the exception of forgetting to put gas in the lawnmower. Pulling the spark plug and cleaning it with some WD-40 will often solve your lawnmower troubles. To remove the sparkplug, pull the wire attached to the end of the spark plug. Then using a crescent wrench or a Ratchet/Socket, unscrew the spark plug from the cylinder. If the spark plug is fouled, wet or black looking, you’ve probably found the source of your non-starting lawnmower.

Use a fine grit sandpaper to lightly sand the metal tab filament (on top of the spark plug) down to bare metal. Make sure to sand all around the edges of the metal tab filament that is located just above the sparkplug electrode. Also ensure that there is a gap between the metal tab filament and the electrode. If you can find a copy of the lawnmower manual determine what the spark plug gap should be and use a feeler gauge to adjust the spark plug gap accordingly. Most of the time, however, if there is a small gap of around 1/16 of an inch between the electrode and the metal tab filament it is probably sufficient for the spark plug to operate properly. Meaning a spark will occur when the pull cord is pulled and when the engine is operating.

Also make sure to check that the spark plug is dry and free of dust and debris. Then hand-screw it back into the engine cylinder and tighten with the wrench or ratchet/socket. Finally push the wire onto the end of the spark plug. Now try starting the lawnmower. With any luck it should fire right up.

Check for Oil in the Lawn Mower

An engine needs oil in it to make sure the engine runs smoothly. It also protects the engine from wear. Consequently make sure that there is oil in the lawnmower and that it is at the proper fill level.

Check that the fuel line is Open

Often at the end of the mowing season most of us turn off the valve associated with the fuel line that feeds gas from the lawnmower’s gas tank to its carburetor.

Clean spark plug as part of spring maintenance on lawnmower

And similarly, at the start of the mowing season, many of us forget we did this. So before attempting to start your lawnmower in the spring make sure the valve is in the ON position so that fuel can flow from the gas tank to the carburetor.

If you have done all of the above and the engine will still not fire, then determine if fuel is getting to the carburetor. Occasionally there can be a blockage that forms in the line, or even worse a hole that forms in the fuel line. Remove the fuel hose from the carburetor and see if gas pours out freely from it. If it does, reattach the gas line. If not, then examine the fuel line. The fuel filter may be clogged or have a hole in it.

Check the Air Filter to See if Clean

Remove the air filter from the lawnmower and see if it needs cleaning. If it is dirty and/or oily feeling then replace it with a new one. If it just dirty, shake it numerous times to knock off the dust. You can also try using a water hose on the air filter to clean it. Just let it fully dry before reinstalling it.

Clean the Carburetor

Disassembling and cleaning a lawnmower’s carburetor is not such a big deal. Usually there is a nut on the underside of the carburetor that can be removed with a small crescent wrench. To clean the carburetor, however, first turn off the fuel line to it.

With the fuel to it turned off, use the crescent wrench to remove the small nut. Then pull the bottom portion of the carburetor off. Use a little WD-40 to clean the inside of this lower portion of the carburetor. Also make sure the float valve that is attached to the upper portion of the lawnmower moves up and down freely. The float valve is a small plastic container about 1-1/2 inch in diameter that hangs down from the top portion of the carburetor.

Once you are sure the carburetor sections are all clean reattach the lower portion of the carburetor to the top portion. Then turn on the fuel line again.

Now attempt to restart the lawnmower.

If your lawnmower still won’t start after performing all of these maintenance procedures, then you probably need to take it to a repair shop. The carburetor may need to be tuned or there could be something wrong with the cylinder or piston. However, from my personal experience these lawnmower maintenance and repair procedures usually work in resolving a non-starting/poor running lawnmower.

Sharpen the blade

Lastly, to ensure nice lawn cutting, make sure to sharpen your lawnmower’s blade. Besides giving your lawn a better cut it will put less stress on the engine. Thus you’ll extend the life of your lawn mower.

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