Lawn Mower Won’t Start after Sitting For Winter

Last Updated on January 7, 2022 by Grow with Bovees

If you are into gardening, here’s something to know. You have to set aside some time for the maintenance of equipment like lawnmowers. Neglect that part of gardening and the price to pay will be quite hefty.

On the other hand, if you just do regular maintenance, it is going to be easy and you can enjoy the benefits of having the right tools for the job. But if you’re reading this, you have probably already learned this lesson the hard way. So, let’s get to damage control. Here is a list of reasons your mower might have malfunctioned.

Out of Gas or Old Gas

If your lawn mower is out of gas, well, you know what to do. Every mower comes with a gas tank of a specific size. Check the owner’s manual to know its capacity. You will also find printed markers on the tank to help you fill to the correct level. Make sure you don’t put too much in the tank. That causes its own set of problems. Make sure to use the correct fuel/oil mix in the engine. You should check whether it needs 50:1 vs 40:1 oil/gas mix ratio, as this can affect the starting of the engine if there is too much oil in the fuels.

Now, if you have old gas in the engine, that’s a problem too. If you forgot or did not bother to empty the gas tank before you put it away for a long time, you will end up with old gas.

It is old if it has been in there for more than a month. The first thing you must do is drain it out and put some fresh regular or premium gas. This is done by draining the gas bowl and gas tank, and then making sure there are no residual particles or grime in the tank. If you are going to leave gas in the tank on occasion, you must consider adding some fuel stabilizer. This helps keep gasoline fresh for almost two years.

Check the Plug

The spark plug is an important component of the lawnmower. It has two electrodes that won’t function well if they are worn out or dirty. This happens if they are wet for some reason or have been covered in grime after combustion (which happens with every use). That’s why cleaning your mower parts after every use is important.

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Now, electrodes can be worn out if they have been used for a long time. The easiest solution, of course, is to replace them. But the spark plug also tells you about other malfunctions if you examine it closely.

There is a lot of dry deposit on the electrodes, which means your fuel-to-air ratio is off or that your engine seal is broken. But if it is the spark plug, remove it from the socket with a wrench and clean the black deposits.

A healthy plug has light brown deposits on the surface. If the plug is wet, that is from excess fuel getting into the combustion chamber. That means it needs servicing, or the choke is stuck on.

Check Carburetor Condition

A lawnmower’s carburetor needs to be clean at all times. This can be done by regular maintenance with a carburetor cleaner spray. It is easy to find and quite inexpensive too.

Start by removing the air filter and give it a good cleaning with the spray. Keep it that way for a few minutes so that the grime gets loosened. Some carburetors have a float bowl which also needs to be clean. To remove those, you must remove the drain plug and take out all the gas from the bowl.

Then you must remove the bowl and clean its surface with the same spray. Sometimes, this is all it takes. But if it doesn’t work, you might have to take the carburetor apart and get into deep cleaning. Make sure you put it back together carefully because otherwise, you will see leaks and unnecessary gases entering its surface.

Clean the Main Jet

A lawn mower engine will not start unless the main jet is clean. To do that, remove the spark plug cap and turn off the fuel valve. Drain the fuel tank by removing the carburetor bowl. Check it for dirt or old gas.

If these individual parts need cleaning, get to it. The fuel flows through the main jet to enter the carburetor and then to the combustion chamber for the lawnmower to work.

Remove this small brass jet with a screwdriver and inspect it. If you find blockages, use the carburetor spray to remove the grime. Push a wire through it if you have to but be gentle. Remove the clogs with the spray cleaner after treating the jet with the wire. That ought to do it.

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Clogged Intake Filter

Your mower is in trouble if the air filter is not clean. The filter has a guard which protects it from the engine and carburetor debris. This includes grass and dirt. But you need to clean the filter from time to time otherwise, your engine won’t start.

You can do this by cleaning or replacing the filters after every 25 hours of usage. The process to remove and replace filters is different for riding lawn mowers and push lawn mowers. Check the manual for the right way to do it.

Check and Change the Oil Anyway

It is best to check and change the oil in your lawnmower when the engine is cold. Start that process by locating the fill cap on the crankcase. Use a clean cloth to wipe the area around the cap even before removing it.

Use a dipstick or a clean cloth to inspect the oil. If your engine comes with a dipstick cap, clean that too with a cloth. Get the accurate reading and put the dipstick back.

When it’s time to change the oil, remove the spark plug and secure it. Locate the oil drain plug which is usually under the deck. On a larger mower, you may need to lift it up using a mower lift, this will make general maintenance much esaier overall. Drain the oil and wipe the area with a clean cloth while making sure no debris falls into the crankcase.

Place an oil pan or newspapers on the floor and tilt the mower to drain the oil out. Twist the drain plug clockwise and tighten the wrench. Add oil, normally SAE 30 or 10W30, you need to check which, in the manual and run the engine to check for leaks. That should fix it.

Use TruFuel Gas to Avoid Old Gas Problems

TruFuel is a high-octane fuel that is built for two-cycle and four-cycle machines. It is a synthetic lubricant and has stabilizers that are free of ethanol. This helps performance and keeps the equipment safe too.

This is recommended because when gasoline with ethanol is left in a fuel tank for a long time, it absorbs water from the atmosphere and causes something called phase separation.

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This separates the gas and oil and the water gets into the engine without lubrication. And at that point, even a fuel stabilizer won’t help. So, it’s best to use fuels like TruFuel which will not degrade the plastic and rubber parts of the engine.

Change the Air Filter as Preventative Maintenance

There are two types of air filters—foam only and dual element. If you have a foam filter, it can trap debris and dirt when the motor oil is used. If your filter is non-oiled, large particles will be trapped. So, you must replace it at least once every three months.

You must replace them even if it does not look like there is damage. Start by removing the screw and taking out the filter. Get rid of the foam and clean the metal parts.

Get the new foam filter and saturate it with new engine oil. Get a clean cloth and remove the excess oil. Assemble the filter once again and reinstall the carburetor.

If you have a dual element filter, remove the knob first. Take the foam pre-cleaner and reinstall the cartridge. Before putting the knob back inspect it. Replace it if there is too much dirt or damage or it isn’t fitting well anymore.

Replace Your Mower’s Spark Plug as Preventative Maintenance

As with most replacements, spark plugs should also be replaced when the engine is cool. Remove the wire of the spark plug and clean the debris off it. The metal must be clear of rust too.

Remove the plug with the right-sized wrench. If it’s too tight, use a lubricant like WD40 or CRC. Measure the gap between the electrodes of the spark plug to make sure it fits with the recommendation of the manufacturer.

Place the new plug with your hands and screw it in carefully with a wrench. Make it firm but not too tight. Also, replace the spark wire and connect it to the spark plug. Run the engine to make sure you did it right.

The Bottom Line

Every part of a lawn mower requires special care and attention. If you get into it, this can be a lot of fun. And the better you understand how it works, the more efficiently you will be able to use it. That also makes maintenance easy and cost effective.