Your mower is getting older and you can no longer get it started. Before you give up on your mower and purchase a new one, check out my list below to get your mower up and running again.
A Scotts riding mower won’t start when it doesn’t get the air, spark, and fuel required.
This may be caused by a plugged air filter, wrong choke setting, dirty carburetor, clogged fuel lines, plugged fuel filter, bad spark plug, faulty ignition coil, or a weak battery.
Keep reading for additional items that can cause your Scotts mower’s starting problem. Follow all safety precautions found in your operator’s manual. This includes removing the spark plug wire prior to performing repairs.
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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.
Reasons Your Scotts Riding Mower Won’t Start
Empty Gas Tank
Your gas-powered riding mower requires gas to run. When the tank is empty, you’ll need to refill it with gas.
I only mention the lack of gas can prevent the mower from starting because, sometimes out of frustration, one can forget the most obvious reasons for a starting failure.
SOLUTION: Fill the mower with fresh gasoline with an octane level of 87-grade or higher. Choose a gas with an ethanol level no greater than 10%.
Bad or Old Fuel
Gas begins to break down and become less effective after about 30 days. It’s important to purchase fresh fuel and consume it within 30 days.
The ethanol included in gas today is an environmentally friendly substance that works fine in most vehicles, but it is not a good choice for the small engine on your Scotts mower.
Ethanol attracts moisture and when that moisture evaporates, gummy deposits can be left in the fuel system to clog fuel lines, filters, and the carburetor.
SOLUTION: Remove the old fuel. A fuel siphon pump works well. Mix a fuel additive in fresh gas before adding it to your fuel tank. Using a fuel additive like Sea Foam is a good idea after running old gas. Read more about the advantages of Sea Foam in this article.
It not only stabilizes gas but also helps clean the fuel system and reduce moisture. After adding this gas and additive mix, start the mower and allow this mixture to work its way through the fuel system.
If you are still unable to start the mower, keep going through the list to determine the cause.
Wrong Choke Position
The choke is a component installed on the mower to restrict airflow. Less airflow is needed to start a cold engine. Engaging the choke closes the choke plate so a higher concentration of fuel is used to form combustion in the cylinder.
When the choke is not placed in the closed position, a cold engine will not start. Likewise, when the choke is not in the open position, a warm engine will not start.
SOLUTION: Make sure the choke is engaged when starting a cold engine and is off when starting a warm engine.
Depending on your model, you will either have to adjust the throttle lever to engage the choke or you will have a separate choke knob.
If the throttle lever is used to close the choke, move the lever to the choke position. Once the engine starts running and warming up, adjust the lever to the full throttle position.
If your model has a choke knob separate from the throttle lever, pull the choke knob out to close the choke. Place the throttle lever in the full throttle position and start the mower. Once the engine starts and warms up, push in the choke knob so the choke is open.
If the choke is in the correct position and you are continuing to have air flow problems, check for a plugged air filter, a stuck choke, or a worn choke cable.
Plugged Air Filter
Your air filter should be cleaned or changed frequently so your engine can continue to pull in clean air. When airflow is blocked because of a plugged air filter, the engine runs hot and searches for air where ever it can find it including air remaining in the crankcase.
A plugged air filter may not only cause starting issues, but it may also cause the engine to overheat, smoke, and cause engine damage.
SOLUTION: Clean your paper air filter and replace it if very dirty or damaged.
Clean a Scotts riding lawn mower paper air filter:
- Remove the filter from the air filter housing. Be careful to not let any dirt fall into the air intake.
- Wipe out any dirt level in the housing with a clean cloth.
- Tap the filter against your hand or solid surface to remove excess dirt.
- Hold the filter up to the light to check to see if light can be seen through every area of the filter. If you cannot see the light, the filter is damaged or torn, or it no longer seals right, you must replace it.
- Install the filter.
Clean a Scotts riding lawn foam pre-filter:
- Quick note: The foam pre-filter is used in combination with a paper air filter to help trap dirt. Never add oil to a pre-filter because the oil will damage the primary paper air filter.
- Inspect the foam pre-filter. If it has dark spots, is brittle, or is torn, it is time to replace it with a new one.
- Wash the foam filter in a water and mild detergent mix. Rinse the filter until the detergent is removed.
- Squeeze dry. To avoid tearing the filter, don’t ring it out.
- Lay flat until completely dry.
- Once dry, it is ready to be installed.
If your mower uses a different type of filter, refer to the operator’s manual or read Guide to Lawn Mower Air Filters.
Bad Fuel Pump
When your fuel tank is lower than the carburetor, the mower will have a fuel pump. This is required to push fuel up to the carburetor.
The fuel pump will have three ports: an inlet port, an outlet port, and a port that is connected to a line off of the crankcase that pressurizes the pump.
You may be able to visually recognize your fuel pump is bad by checking the pump for small cracks or fuel leaking. You will have to replace the fuel pump if you see cracks or fuel leaking outside of the pump.
If the fuel pump appears to be in good condition, you need to check the fuel lines to ensure fuel is getting to the fuel pump and fuel is being pumped out of the fuel pump.
SOLUTION:
Verify you are getting fuel to the fuel pump:
- Turn off the fuel valve or use pinch pliers to stop the flow of fuel. (Not every mower has a fuel valve).
- Disconnect the line from the inlet port of the fuel pump and place it in a container that sits lower than the fuel tank.
- Unclamp or turn on the fuel valve and check to make sure fuel is flowing out of the tube into the container.
- If you are not getting fuel, check the fuel lines or the fuel filter for blockage.
Verify your fuel pump is pumping fuel to the carburetor:
- Reinstall the fuel line you took off by connecting it to the fuel pump inlet.
- Remove the fuel line from the carburetor.
- Place the tube in a container, start the lawn mower, and watch the end of the fuel line to make sure fuel is being pumped out of the fuel line into the container.
- You should have a steady flow or pulsating flow of fuel coming out of the fuel line.
- Replace the fuel pump if it is unable to consistently pump fuel out of the outlet port.
Plugged Fuel Filter
A fuel filter strains the fuel coming out of your fuel tank and running through your fuel system to keep out any dirt or debris.
Old fuel can leave gummy deposits when it evaporates. This along with dirty fuel may plug the fuel filter. A plugged filter will keep a sufficient amount of fuel from passing through the filter and may cause your Scotts starting problem.
SOLUTION: A fuel filter that is plugged must be replaced.
Clogged Fuel Line
Old fuel that gummed up can become lodged in your mower’s fuel line. Test flow through the fuel line by stopping and starting fuel flow as you check the fuel flow from fuel line sections.
SOLUTION: If you find a line with a fuel restriction, shut off the fuel supply. Remove the fuel line from the mower. Spray a carburetor cleaner into the tube and use compressed air to blow air through the tube until the line is no longer clogged.
The carburetor = cleaner is used to loosen the restriction. The air is used to dislodge it and push it out of the line. Repeat these two steps as needed. Replace the fuel line when you are unable to remove the clog.
Dirty Carburetor
The carburetor is an essential component of your lawn mower. Its function is to make sure your engine receives the right mixture of gas and air to create combustion.
Without this correct ratio of gas and air, your lawn mower may run rough and may not be able to start.
SOLUTION: Your carburetor can be replaced or cleaned. Most of the time, cleaning your carburetor will do the job, and your mower will be up and running again.
If you find any damaged parts, you may need to replace them using a carburetor rebuild kit. Replace the carburetor when cleaning the carburetor does not work.
You can find steps for cleaning your carburetor in this article.
Bad Battery, Loose Cables, or Corroded Terminals
If the mower won’t even turn over, check the battery, cables, and terminals. The battery must be charged at a reading of 12.7 volts or greater. Loose cables and corroded terminals can contribute to starting issues.
SOLUTION: Clean corroded terminals in a baking soda solution containing 2 cups of water and 3 rounded tablespoons of baking soda. Use a wire brush to scrub the terminals clean.
Test your battery with a multimeter. If you receive a reading of less than 12.7 volts, you must charge your battery. Read more about the steps and items needed to charge your battery here. If your battery does not hold a charge, you will need to replace it with a new battery.
Bad Safety Switch
A mower uses several safety switches in order to keep you safe when you are operating the lawn mower. These switches can become faulty and cause your lawn mower to not start.
SOLUTION: Test the switch using a multimeter or you can temporarily bypass the safety switch to identify a bad switch. Do not operate a mower without the safety switch installed for your safety. Always have safety switches installed and working on your equipment.
Bad Spark Plug or Loose Connection
Another reason your Scotts mower won’t start may be due to a bad spark plug connection or a damaged spark plug. A dirty spark plug can also cause intermittent spark problems.
SOLUTION: Remove your spark plug(s) and inspect it for signs of carbon buildup, cracked porcelain insulator, or burnt electrode. Replace it with a new spark plug if you find any of these conditions.
Make sure to gap them according to the manufacturer’s specifications. Securely attach the spark plug wire once you are done troubleshooting and repairing the mower.
A loose wire or wrong electrode gap can cause a starting or intermittent running problem.
Bad Ignition Switch
You insert the key into your ignition switch and turn it only to find your mower doesn’t start or even turn over. The ignition switch could be the problem.
SOLUTION: You can use a multimeter to test the ignition switch. Replace the switch if bad.
Faulty Ignition Coil
The ignition coil provides voltage to the spark plug so it can fire and start the engine. The engine will not start if the spark plug isn’t able to fire.
SOLUTION: After you verified your spark plug is in good condition, check the continuity of your ignition coil using a multimeter. Replace the ignition coil if you find a break in the continuity.
Bad Starter Solenoid
A lawn mower solenoid is an electromagnetic switch that is like an on-off switch that actuates the starter motor to turn over the engine. A click or hum when turning your ignition key is an indication to check your solenoid.
Another indication your riding mower solenoid may be bad is when a wire attached to your solenoid gets hot and begins to smoke or melt.
SOLUTION: Test your Scotts mower solenoid by following the steps here. Replace your solenoid if it is found to be bad.
Faulty Charging System
While the charging system isn’t the main reason your Scotts mower won’t start, it can contribute to a weak battery that prevents the mower from starting.
When the charging system fails to charge the battery, the battery may not be able to start the mower the next time you go to use it.
A bad stator or alternator can be the problem along with several other electrical parts. Read this article to test your charging system here using an ohmmeter.
SOLUTION: If you find the problem is in your charging system, have a small engine mechanic identify what is the actual cause of the failure. It could be several different items and you will just be guessing at the problem which gets pretty expensive.
Bad Gas Cap
The fuel tank must be able to vent allowing air to pass into and out of the tank to keep the tank pressure and atmospheric pressures equal.
The vent for the fuel tank is located in the gas cap. When the vent becomes plugged, the fuel tank will form a vacuum keeping fuel from getting to the carburetor.
SOLUTION: Replace a broken gas cap that is no longer venting properly.