You’re out mowing the lawn as usual when your Snapper mower just suddenly quits. You may have experienced smoking or your mower running sluggish before it shut down. It may have just shut down without any advanced signs that it was having trouble. Either way, you need to identify the problem and resolve it so you don’t cause any further damage to your mower by continuing to run it.
A Snapper lawn mower may start then die when old fuel has clogged the fuel system restricting fuel to the engine. A plugged air filter, insufficient oil level, plugged mower deck, bad spark plug or faulty charging system can also can a Snapper mower to shut down after running.
Keep reading for a complete list of items that can cause your mower to stop running. When diagnosing and repairing your problem, take safety precautions to prevent your mower from running or moving. This includes removing the spark plug boots and ignition key, if your mower uses one, along with setting the parking brake. Refer to your operator’s manual for additional safety guidelines.
Reasons Your Snapper Lawn Mower Starts Then Dies
Bad or Old Fuel in Your Snapper Mower
Using gasoline that has been sitting in your Snapper mower or stored for a long period of time becomes less effective and cause problems in your fuel system and engine. Most gasolines on the market today contain ethanol. This is a corn-based product added to gasolines to make them more environmentally friendly.
While the addition of ethanol to gasolines is generally fine to run in your vehicle, it is not good to run in the small engine on your Snapper mower. Because of this, make sure your unleaded gasoline doesn’t contain any more than 10 percent of ethanol. Ethanol attracts moisture from the air. This moisture, when evaporated, can leave a gummy substance in your Snapper mower causing fuel restrictions.
Over time, the ethanol and fuel mixture separates from the gasoline and sinks to the bottom of the fuel tank. This mixture can cause your engine to run hot and damage the engine.
Make sure you run fresh fuel through your mower. If you know you are unable to consume the fuel within 30 days, add a fuel additive to stabilize your fuel. I choose to use it in every tank of fuel whether my fuel is sitting for long periods or not.
The fuel additive I use, called Sea Foam Motor Treatment, not only stabilizes the fuel, it also has cleaning agents and reduces moisture. Read more about it in my article on the advantages of Sea Foam in a lawn mower.
Plugged Air Filter in Your Snapper Mower
Your Snapper mower requires air to start and run. When airflow is restricted, your mower will die. It’s good practice to replace your air filter annually and regularly clean it throughout the mowing season. Failing to do so can cause your mower to overheat and cause significant engine damage.
Clean your air filter by removing it from the air filter housing. Be careful not to let any dirt or debris fall into the air intake. Wipe out any dirt remaining in the housing with a dry cloth. Proceed with the instructions for your air filter type:
Clean Snapper Mower Paper Air Filter Element: Tap the filter against a solid surface to loosen and remove as much dirt as possible. Next, hold the filter up to a light source to check if you can see light shine through the filter. If you can, go ahead and reuse your air filter. If you cannot, you must purchase a new filter. Replace the air filter and reinstall the cap on your housing.
Clean Snapper Mower Foam Filter Element: Inspect your filter for brown spots, tears or a dry brittle condition. If you find any of these items, purchase a new filter for your Snapper mower. If your filter is in good condition, proceed with cleaning by using a mild dish detergent and water to remove dirt. Rinse the filter to remove all soap and lay flat to dry.
Once the filter is dry, use a foam filter oil to coat the filter. You do not want the filter to be dripping with this oil. Wring out any extra oil and replace the filter in your housing. Note: You need to add a filter oil to a new air filter. This oil helps prevent dirt from passing through the foam filter.
Clogged Fuel Lines or Fuel Filter on Your Snapper Mower
Dirt and deposits from running old fuel can plug your fuel filter and fuel lines. Your fuel filter should be replaced once a year. If you find your filter is plugged, replace it with a new filter. Install the new filter with the arrow on the filter pointed in the direction of your fuel flow.
Check your fuel lines to make sure you don’t have kinks in the lines or clogs. To find restrictions in your fuel lines, use your fuel shut-off valve or crimp your fuel line to start and stop flow while checking each section of line.
With your fuel flow stopped, remove the end of a section of line that is furthest from the fuel tank and place it in a container. Start your fuel flow to see if fuel is running into the container confirming flow. If you don’t have a good supply of fuel running into the container, you will need to remove the clog or replace it with a new fuel line.
With your fuel supply off, remove the section of fuel line with the clog from your Snapper mower. Spray carburetor cleaner into the line to help loosen the restriction. Then blow compressed air into the line to remove the blockage. If this doesn’t work, you will have to replace the line with new fuel line.
Snapper Mower Carburetor is Dirty
The carburetors main purpose is to regulate the amount of fuel mixed with air to form a combustion in your engine. When the carburetor doesn’t work properly, your mower can start then die. The carburetor becomes dirty from running old fuel that sits in your carburetor causing gummy and hard deposits to form. This will cause components on your carburetor to restrict the flow of fuel.
If your carburetor is dirty, you can clean it using my step-by-step guide to clean a Snapper carburetor. Before you tear your carburetor apart, make sure you are getting fuel to the carburetor. Once that is confirmed, remove your air filter and spray carburetor cleaner into the air intake. Start your mower. If you find it dies after running, disassemble your carburetor and clean it.
Plugged or Broken Cooling Fins on Your Snapper Mower
Your Snapper mower can start and then die when your mower’s engine gets hot. Check your engine cooling fins. They may be plugged with debris or broke. The cooling fan exists to push air to the area around your engine block and cylinder head to keep it cool.
Plugged cooling fins can restrict the amount of air circulating around your engine. In addition to cleaning the cooling fins, you must clean around the engine and engine shroud. Make sure the heat shield is securely attached. Be careful when working around your engine as it can be hot.
Insufficient Engine Oil Level in Your Snapper Mower
Your mower requires a specific amount of engine oil in the crankcase for the engine to run at its best. Most people know you can develop problems when your engine oil becomes too low, but don’t know you can also have problems with there is too much oil in the crankcase.
Too Much Engine Oil in Your Snapper Mower
Check the engine oil level in your mower. Too much engine oil in your Snapper lawn mower will cause pressure to build in the crankcase. This can cause your mower to overheat and shut down. Read more about the impact of too much oil in your Snapper mower.
Remove some engine oil through the drain plug or oil filter. You can also use an oil evacuator or turkey baster to suck oil through the engine oil fill area. Check the engine oil level on the dipstick. Continue to add or remove oil until the oil level is at the full line on your dipstick.
Too Little Engine Oil in Your Snapper Mower
You may have developed an engine oil leak or have a problem in your engine where it is using or burning oil. When you don’t have enough oil to keep the internal engine parts sufficiently lubricated, friction starts to build creating heat. This heat can overheat your engine and cause it to die. The heat can be so hot, your internal engine parts will start to melt.
Here’s the bad news. If your engine shut down because of a lack of engine oil, chances are significant damage was done. Your best solution here is to take your mower to an experienced small engine mechanic to tear down your engine and perform tests to determine how much damage was done.
Bad or Dirty Spark Plug on Your Snapper Mower
A dirty spark plug can foul out causing your Snapper mower to die. You may have been able to get enough spark to start your mower, but not enough to continue to run your Snapper. A plug that is not properly gapped or the spark plug wires are not secure can also cause a running problem.
Clean your spark plug tip. If you find the tip of your spark plug is very dark, has a burnt filament or is damaged, replace your spark plug. Make sure the plug is air gapped following the engine manufacturers specification. Securely attach your spark plug wires
Bad Ignition Coil on Your Snapper Mower
The winding on the ignition coil can separate and short out when your mower is hot. When this happens, the spark plugs are unable to get the voltage they need to create spark. This can cause your mower to die after it’s been running a while.
Identify a bad ignition coil using an ohm meter to check for a break in continuity. Replace the ignition coil if you find there is a break.
Choke is in the Wrong Position on Your Snapper Mower
The choke is used to allow more fuel to enter the combustion chamber by restricting air flow. This is needed to start a cold engine. If you leave your choke on after the engine starts and heats up, your engine will shut down. Make sure your choke lever is in the right position.
Snapper Mower Battery Not Charging
Your mower will start and die if your battery won’t hold a charge or you have a problem with your charging system. Make sure you are running your engine at a high engine speed. Don’t allow your mower to idle for long periods of time. It requires the power of the engine to charge your battery.
There are some steps you can take to check the condition of your battery and charging system which I explain this this article. If after performing these tests, you find you have a bad battery, replace your battery. When you find the charging system isn’t working right, I highly recommend having an experienced mechanic diagnose and repair the problem.
I did say an experienced mechanic. There are so many components that can cause the charging system to fail that, unless you know the charging system, parts can be thrown at it hoping to fix the issue. Electrical components can get expensive and most likely can’t be returned because they are electrical parts.
I’ve seen inexperienced mechanics throw parts at a mower trying to fix a charging system problem. The sad thing is the customer is the one that must pay the bill including the unnecessary parts and labor. Make sure your mechanic is experienced with the charging system on your Snapper lawn mower.
Bad Snapper Mower Gas Cap
A gas cap that can no longer vent allowing air to pass through the cap can restrict fuel flow and cause your Snapper mower to shut down. When the vent in the gas cap is plugged, the fuel tank forms a vacuum not allowing gas to flow to the engine.
Run your mower with and without the cap for periods of time to see if your cap is the cause of your Snapper mower dying. If you remove your fuel cap and your mower starts and runs and then replace your cap and your mower eventually shuts off, you may have a problem with your cap.
You can try to clean your fuel cap to remove the clog or just replace it with a new fuel cap.
Plugged Snapper Mower Deck
A mower deck that is plugged full of debris can actually cause your Snapper lawn mower to shut down. This is because the engine must work harder to turn the blades through a deck full of debris. This can cause your engine to overheat and shut down.
Prevent this from happening by regularly scraping your deck to keep it clean. Avoid mowing in wet conditions as wet grass clumps and sticks to your mower deck. You can try using a deck spray to minimize grass buildup. Deck sprays are not a miracle product that prevents all buildup, it can minimize the amount of debris collecting under the deck.
Performing an annual service and regular inspections for your Snapper mower can help prevent some of the problems that can cause your mower to die after running a while. Checking your engine oil before each time you use your mower can provide early warning signs you have problems with the engine.
A low engine oil can indicate you have an oil leak or your mower is consuming or burning oil. Catching engine problems early can prevent significant engine damage. For other items you should be checking regularly read my article “Lawn Mower Checklist for a Successful Cut“.