Lawn Mower Repair Service Frequently Asked Questions


My lawn mower has been stored all winter and now it won’t start. What could be wrong?

When most mowers are stored for more than 3 months, their gasoline becomes stale and will begin to phase separate. Phase separation is the process of the gasoline breaking down into different chemicals and separating from one another. With the ethanol blend of fuel today, phase separation occurs when the gasoline is exposed to water. It can be either water that enters the tank or through humidity. The ethanol in the gasoline will attract that water and separate from the rest of the chemicals in the fuel and you may see one or more layers of fluid in the tank or carburetor.

Once this process begins, the highly volatile chemicals in the gasoline will evaporate and then the fuel will dry up and plug important parts of a carburetor such as the emulsion tube, idle and high-speed jets and transitions ports.

I tipped my lawn mower over and now it won’t start.

When you tip your lawn mower over towards the carburetor to scrape the deck or remove the blade, fuel and oil can drain out through the carburetor. The oil will saturate the air filter and the fuel will do the same. Now the lawn mower will not get as much air to start and will run rich if at all. If you let the lawn mower sit level, it may start after a while. But first check the oil level before you try to start it.

My lawn mower will not go in forward or reverse.

Drivetrain problems like this are fairly common. Drive belts wear out, drive pulleys seize up and transmissions can wear out. Make sure the brake is not on, the shifter is in gear, the tow rod is pushed in which is the rod on the back of the mower on a riding mower. If those things are all working, then it is time to have your lawn mower inspected by a lawn mower mechanic to determine the problem.

My lawn mower is not getting any spark.

If you are using a spark tester and you can visually see that there is no spark, then obviously you have an ignition problem. Make sure that the engine has the correct amount of oil in it and that the safety bail is held down on a push or self-propelled mower. If you have a riding mower, be sure you are seated on the mower and that you have the brake pedal down, the PTO switch off, the gear in neutral and the deck raised.

My lawn mower is not getting any fuel.

The first thing to check is for fuel in the fuel tank. If there is fuel in the tank, then it may be a carburetor or fuel pump issue. The fuel cap could also be plugged and preventing the tank from venting properly.

My lawn mower starts and then dies.

This is more common in the springtime after a lawn mower has sat all winter. The gasoline could be going bad or have water in it. The carburetor could also be plugged up with phase separated fuel. The choke could be malfunctioning as well.

My lawn mower runs for a while and then dies.

This is a more complex issue to resolve and requires some thorough diagnostic checks to figure it out. Ignition, oil and fuel problems can cause your lawn mower to just shut down.

My lawn mower is hard to start.

Bad fuel, bad spark plug, valves out of adjustment are a few of the things that cause this problem.

What type of oil do I use in my lawn mower?

As a general rule, most American brands of engines such as Briggs & Stratton, Kohler and Tecumseh call for SAE30 weight oil. Japanese engines such as Honda and Kawasaki normally call for 10W-30 weight oil.

Chinese brand engines normally follow the Japanese brands and all for 10W-30.

Follow the recommendations of the engine manufactures owners manual for the correct oil type and viscosity. If you are using your lawn mower in temperatures below 40 degrees, you will need to change to a thinner oil such as 10W-30.

Follow these links for each engine manufacturer for their recommendations.

Briggs & Stratton




How often should I service my lawn mower?

Every lawn mower should have an annual service performed on it. Most engine manufactures recommend the oil changed at 25 hours for small engine and 50 to 100 for larger ones with an oil filter system. Other parts of the machine need to be cleaned and lubricated such as the steering linkages and wheel bearings.

The pull cord broke on my lawn mower.

This can normally be repaired by replacing the cord or by replacing the starter assembly if the spring inside of it is broken.

What spark plug does my lawn mower engine use.

All of the engine manufactures such as Briggs & Stratton, Honda, Kohler and Tecumseh have their own specific spark plug recommendations and gaps for their spark plugs. Refer to your documentation that came with your engine for your lawn mower.

My battery keeps running down on my lawn mower.

Today’s batteries don’t last for more that 3-4 years. Your battery could be beyond its useful life, you have a charging system problem, a broken wire or a short in the wiring system.

I turn the key and my lawn mower does nothing.

Is your battery dead? Is the main fuse blown? Do you have all the controls set properly and you are sitting in the seat?

Is my lawn mower under warranty?

Review your booklet that came with your lawn mower. Many lawn mower manufactures will warranty residential lawn mowers for a certain period such as 2 year limited warranty and only 1 year if it is used commercially.

Is my lawn mower engine under warranty?

Review your booklet that came with your lawn mower engine. Many lawn mower manufactures will warranty residential lawn mower engines for a certain period such as 2 year limited warranty and only 1 year if it is used commercially.

 How does water get in my lawn mower fuel?

Water can enter your fuel in a few different ways. It can come from the gas station when you pump it into your gas can and then you pour that into your fuel tank. It can also come from the humidity in the air and enter through the vent on the fuel tank.  You can also get water in the fuel tank when you wash your lawn mower and it enters through the vent or gas cap under pressure.

I hear clicking when I try to start the lawn mower.

That clicking is the starter solenoid attempting to provide power to the starter. There is either a problem with the starter or the electrical system.

My mower backfires after I shut it off.

On most riding lawn mowers, there is a solenoid valve called an Anti-Backfire valve or solenoid. This is controlled by the key switch when you turn the lawn mower off. This can cause the problem but there are other things like the valve clearances and what fuel you are using and carbon in the cylinder head.

I smell rubber burning when I am mowing.

Burning rubber is caused by a belt that may have come out of alignment, a pulley may be freezing up or debris is caught in the belt area. The belt could also be out of adjustment or hitting the belt guard. It could also be slipping.

I hear a grinding noise when I am mowing.

There are many things that can cause this issue. Worn pulleys, worn PTO clutch and deck spindles that are wearing out are the most common. The transmission could also be showing signs of age.

I hear a squealing noise when I turn the blades on.

This is most likely a belt slipping. The belt could be wearing out or it could be the wrong belt is installed on the lawn mower. The tensioners could be bad as well.

How often should I sharpen my lawn mower blade?

If you are mowing a small residential yard, 1 to 2 times a year. A larger yard 2 or more times a year. Your blade must be kept sharp. If the grass in your area is tough, you will need to sharpen your blade more often.

I hit something and now my lawn mower won’t start.

Hitting an object with your lawn mower blade often shears the flywheel key and affects the timing of the engine. This can also bend the crankshaft. Your mower will need to go to the repair shop for a diagnosis.

My lawn mower cuts evenly.

If you have a push or self-propelled lawn mower, check the settings on the wheel adjusters. If they are all set to the same setting, you may have a problem with your lawn mower blade or crankshaft.

If you have a riding lawn mower, make sure that the tires have the proper amount of air in them and that the deck is level. Make sure that the blades are installed properly as well.

When I turn the key on the lawn mower, nothing happens.

Is your battery dead? Is the main fuse blown? Do you have all the controls set properly and you are sitting in the seat?

How much is it going to cost to fix my lawn mower?

Until the lawn mower is properly diagnosed, the cost for the repair is unknown. Let the lawn mower technician provide a full inspection of the lawn mower and perform their diagnostic checks to ensure you get an accurate assessment of repair costs.

Why does it cost so much to fix my lawn mower?

Lawn mower parts prices have risen dramatically over the years and labor rates have as well to cover things like insurance, shop utilities and rent.  Lawn mowers have also become more sophisticated which require different test equipment, software and more diagnostic time.