Lawn Mower Won’t Start After Sitting. Here’s What to Do …

We know it’s annoying when your lawn mower doesn’t want to start up after being parked.

This unexpected hurdle can quickly put a damper on your plans for a well-manicured lawn.

Eventually, small engines can incur problems from freezing, particularly if left to sit over volatile weather periods or seasonal changes.

Old fuel, a clogged carburetor or even a dead spark plug are all typical culprits for this issue.

A little regular maintenance and a few other simple checks will usually get the mower running again with minimal fuss.

Knowing these potential causes will help to save you time and money by preventing unnecessary trips to a small engine repair shop.

So, let’s get down to what might actually work. Follow these to pinpoint the malfunction, repair it, and get your lawn mower back to working perfectly.

Common Reasons for Lawn Mower Won’t Start After Sitting

Stale or Insufficient Fuel

Fuel issues are a leading cause of a mower that won’t start. Gasoline can go stale if left sitting for several months, losing much of its combustibility.

Reason 1 – Lack of Fuel Always check the fuel level as a first step. If you find the tank is bone dry, this is an easy, one-step fix—just fill up your tank with new gasoline.

If there is stale fuel in there, drain it and refill with fresh fuel. Adding a fuel stabilizer when storing your mower will help to ensure gasoline stays fresh for up to a year. This is particularly convenient if you don’t use your mower on a regular basis.

Dirty or Clogged Air Filter

An air filter that is full of dirt and debris restricts airflow, choking the engine. Check the air filter. Start here.

If it appears dirty or full of grass, etc., lightly tap it to remove buildup. If your mower has washable filters, clean them in soapy water and allow them to dry thoroughly before reinstalling.

If the filter is ripped or heavily soiled, replace it. Replacing it with a new one will make a world of difference. Simple maintenance—such as inspecting it after every few uses—will keep you from having headaches in the future.

Faulty Spark Plug

A malfunctioning spark plug may affect ignition. Examine it carefully for any buildup (build up may be a fire hazard) or wear.

Black, sooty deposits usually indicate it’s fouled. Scrub it with a wire brush and remember, set the gap to ensure proper ignition.

If cleaning it does not fix the issue, replace it with a new one. It’s a really easy and cheap repair you can get that will have a big impact.

Blocked Carburetor

The carburetor is responsible for mixing air and fuel, so any blockages can quickly lead to major issues. Signs such as poor idling or fuel leakage usually indicate a carburetor issue.

Use a carburetor cleaner to clean out the carburetor and for tough clogs, compressed air can do the trick.

If this cleaning process doesn’t fix the problem, a rebuild will need to be completed in order to get your carburetor working again.

How to Troubleshoot Starting Problems

If your lawn mower is refusing to start after a season of inactivity, don’t fear. This usually means that some preventative maintenance has been neglected. Let’s go through each one to get it up and running again.

1. Check Fuel and Replace if Needed

Usually, it’s old gas that’s to blame. Old fuel from last season can break down and become ineffective, so emptying the tank is crucial. First, check to make sure you’re using the correct type of fuel—most mowers only need regular unleaded gas.

Either use a siphon to drain old fuel or use the drain plug if equipped, and refill with fresh gas. A funnel minimizes drips and spills when pouring. Monitoring fuel levels can help avoid shutdowns halfway through a mow.

This one easy step is a great way to fix the problem right off the bat.

2. Inspect and Clean the Air Filter

If your car’s air filter is clogged, it can restrict airflow, making it hard for your engine to perform.

Start by taking off the air filter cover, typically secured with screws or clips. If your filter is washable and reusable, gently bang it against a hard surface to knock off any loose debris.

Otherwise, clean it with soapy water, and dry it completely before reinstalling.

Do replace it if it’s really filthy or torn up. Last, always make sure the filter is seated properly in its housing to prevent dirt from getting into the engine.

3. Examine and Replace the Spark Plug

This is another key component for starting since the spark plug is responsible for igniting the fuel-air mixture.

Remove it with a socket wrench and check for wear, fouling, or soot accumulation. A wire brush does a good job of cleaning it up.

If it appears frayed or broken, it’s better to err on the side of caution and replace it entirely.

Selecting the right replacement spark plug for your mower will ensure it starts reliably and runs smoothly.

4. Clean or Repair the Carburetor

Anytime there are fuel delivery problems, they usually go back to the carburetor. Turn off the fuel valve, disconnect the line, and remove the carburetor.

Use an aerosol spray of carb cleaner on everything, focusing on the jets and needles.

If you have any small clogs, compressed air can help clear them away.

After cleaning, put everything back together carefully to prevent everything from being misaligned, which can cause friction and disrupt fuel flow.

5. Test and Charge the Battery

If you have an electric-start mower, test the battery with a multimeter to make sure it has the correct voltage.

If it’s low, charge it up completely and retest. If you notice your battery not holding a charge, consider replacing it.

Somewhat surprisingly, proper voltage is key to getting consistently reliable starts.

6. Clear Debris from the Mower Deck

Grass clippings and leaves can accumulate underneath the mower deck, which decreases cutting performance. If there’s still debris, use a scraper or stiff brush to knock off tougher buildup.

Routine cleaning immediately after each use will help your mower run more efficiently.

Maintenance Tips to Prevent Starting Issues

If you’re tired of dealing with the hassle of a lawn mower that won’t start, simply maintain your mower properly.

This is doubly true when it’s been parked for some time. Just a handful of easy, routine maintenance moves will go a long way.

Change Oil Regularly

Just like your car, changing the oil is one of the simplest things you can do to maintain your mower and help it operate efficiently. Change the oil based on the manufacturer’s guidance, usually every 25 to 50 hours of operation.

Be sure to refer to the manual for the correct type and viscosity of oil, which is vital to proper engine lubrication and performance. Making it a practice to check the oil level before every use is another good habit to adopt.

It allows you to detect low levels in advance, avoiding costly wear and tear. When it’s finally time to change that old oil, be sure to bring it to an oil recycling center. This makes the world safer from environmental pollution and degradation.

Use Fresh Fuel Always

Fuel quality has a large impact on starting problems. Turning to fuel-related starting issues, old, stale gas can gum up the engine and make starting a hassle.

Make sure you’re always using fresh gasoline every time you fill up. Don’t store fuel longer than 30 days unless you use a stabilizer.

Fuel stabilizers are inexpensive and allow you to store gas for a year or more without causing harm.

So, make it a point to inspect your fuel supply on a regular basis for any warning signs of contamination or aging. If the gasoline smells sour or has separated, it’s time to get rid of it.

Store Mower in a Dry Place

How and where you store your mower makes a difference. A dry, sheltered space such as a garage or shed prevents it from exposure to moisture.

Moisture is the enemy of electrical connections, which can lead to rust and other issues. Store the mower under a breathable tarp to keep dust and moisture away without causing condensation to build up.

Wherever you can, raise the equipment on a platform to avoid exposure to wet soil. Plenty of airflow in whatever storage space you’re using ensures your vehicle is dry and free of humidity.

Additional Maintenance Tips

• Remove clumps by cleaning the mower deck and blades after each use.
• Regularly check and replace air filters to maintain airflow.
• Keep an even cut by regularly inspecting and sharpening the blades.
• If you don’t address loose bolts or screws, you risk wear and tear from vibrations.

Conclusion

So getting your lawn mower back up and running again shouldn’t be a daunting chore.

The majority of starting problems can be attributed to straightforward factors such as stale gas, a dirty filter, or a weak spark plug.

Troubleshooting these common culprits can prevent an unnecessary trip to the repair shop.

You’ll save money long-term! Regular maintenance will ensure your mower runs like new for years to come.

Change the oil, clean that air filter, check the fuel and you’ll have a machine that’s always ready to roll!

Keep your mower well-maintained, and it will help you whip your lawn into shape.

If you are still having issues, contact us for professional assistance. Some simple steps today will save you headaches tomorrow and ensure you have the lush, beautiful lawn you want, when you want it.

Frequently Asked Questions

Why won’t my lawn mower start after sitting for months?

Old gas, dirty air filter or a dead spark plug are the most common culprits. Rule these out first before you go down the rabbit hole into more complicated problems.

How can I tell if the gas in my lawn mower is bad?

Gas that has been sitting for more than 30 days can go bad. Watch for a rancid odor or cloudiness. If your mower has been sitting for a long time, replace it with fresh gas.

What should I do if the air filter is clogged?

Remove the air filter and check its condition. If your air filter is especially dirty, consider cleaning it with soap and water or replacing it to ensure your machine is in top shape.

How can I troubleshoot a dead spark plug?

Remove the spark plug and check it for wear or carbon buildup. Replace if it’s frayed or clogged with grass or dirt.

Can the carburetor cause starting problems?

So yes, if the carburetor is clogged it could keep it from starting. Clean it with a carburetor cleaner or have it professionally serviced.

How often should I perform lawn mower maintenance?

Change the oil and filter as well as other basic maintenance items each season or every 25 hours of operation, whichever comes first.

What’s the best way to store a lawn mower for the off-season?

First, empty the gas tank and give your mower a good cleaning. Finally, keep it in a dry, covered space to prevent rust and other wear and tear.