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This is Why Your Craftsman Lawn Mower Won’t Stay Running (Solved!)

You’re mowing the lawn when the lawn mower stops running. Sometimes letting it sit for a while before trying to start it again will work, but it doesn’t always stay running. Trying to get your mower to start after it keeps shutting off can get pretty frustrating, especially when it’s taking up much of your day.

A Craftsman lawn mower won’t stay running when old or bad fuel plugs the fuel filter, clogs the fuel lines, or causes the carburetor to fail. A bad spark plug, bad battery, faulty charging system, bad fuel cap, plugged air filter, incorrect choke setting or faulty ignition coil can also cause a Craftsman mower to not stay running.

Follow the safety guidelines found in your operator’s manual before performing any work on your Craftsman mower.

Craftsman lawn mower won't stay running

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Follow all safety instructions provided in your equipment operators manual prior to diagnosing, repairing or operating. Consult a professional if you don’t have the skills, knowledge or are not in the condition to perform the repair safely.

9 Reasons a Craftsman Lawn Mower Won’t Stay Running

Bad or Old Fuel in a Craftsman Lawn Mower

Running bad fuel or fuel that has been sitting around for a long time can have negative effects on your mower. Fuel becomes less stable and attracts moisture from the air. This can cause corrosion in the fuel system.

The ethanol and moisture in the fuel system will leave behind gummy deposits that will clog the fuel system preventing fuel from getting to the engine. Read more about the right type of gas to use in your Craftsman lawn mower here.

Fuel Restriction in a Craftsman Fuel Components

Clogs can develop in the fuel components that can restrict fuel flow. Without sufficient fuel, your Craftsman mower will die. Old fuel, dirt and debris in the fuel system can result in the following:

  • Clogged fuel lines
  • Plugged fuel filter
  • Bad fuel pump

To read more about items that cause fuel restrictions in your Craftsman and how to diagnose and fix them, check out This is Why Your Craftsman Mower Isn’t Getting Fuel.

Dirty Carburetor on a Craftsman Lawn Mower

The carburetor regulates the amount of fuel that is mixed with air to form a combustion in the cylinder. When a carburetor is dirty from old fuel, the small parts that allow it to function can become plugged or stuck. Your lawn mower will not be able to get sufficient fuel. It will begin running sluggish or won’t stay running.

Before you remove the carburetor from the lawn mower, perform these quicks steps to isolate your fuel problem to the carburetor.

  • Confirm you are getting fuel flow to the carburetor and don’t have a fuel restriction elsewhere in the fuel system.
  • Remove the air filter and spray carburetor cleaner into the air intake. Start your mower. If it runs fine and then dies, there is a good chance your carburetor must be cleaned and inspected for any failed parts.

You can find instructions on cleaning your Craftsman mower carburetor here.

Plugged Air Filter in a Craftsman Lawn Mower

With all the dirt and grass clippings that get thrown into the air when mowing, the air filter can become plugged. It’s important to regularly check and clean the filter. When your engine isn’t able to get the clean air it requires, it will fail to stay running.

Not only will running a dirty air filter cause running problems, it can cause significant engine damage. Keeping the filter clean and replacing it with a new one when needed is a small investment in time and money towards keeping your mower running at its best.

Replace your air filter annually and clean it several times throughout the mowing season using these steps:

Clean a Craftsman lawn mower paper air filter:

  • Remove the air filter from the housing.
  • Wipe out any dirt remaining in the housing. Be careful to not let any dirt fall into the air intake.
  • Tap your filter against a solid surface. What you are trying to do is knock as much dirt out of the filter that will come loose and fall out.
  • Hold your air filter up to a light source and make sure you can still see light shine through the paper element. If you can, go ahead and reuse your air filter.  If you can’t, it’s time to buy a new one.
  • Reinstall the air filter and attach your air filter housing cover.

Clean a Craftsman lawn mower foam air filter:

  • Remove the air filter from the housing.
  • Wipe out any dirt that is in the filter housing. Don’t allow any dirt to fall into the air intake.
  • Inspect your filter. If you find any dark spots, tears or your filter is dry and brittle, you must replace your filter with a new one. If it appears to be in good condition proceed with cleaning it.
  • Wash your foam filter with water and a mild dish soap. Rinse to remove the soap from the filter.
  • Lay flat to dry. Placing your filter in the sun will help speed up the drying process.
  • Once the filter is completely dry, coat it with a foam air filter oil. You want it completely covered with oil, but you don’t want it to be dripping of oil. If you get too much oil on the filter, ring out the extra oil or use a paper towel to absorb excess oil.
  • Reinstall the air filter and attach your air filter housing cover.

Choke Set in the Wrong Position on a Craftsman Lawn Mower

If your mower has a choke lever, it might be set in the wrong position. The choke restricts air flow to allow a higher concentration of fuel into the combustion chamber when starting a cold engine. Once the engine is warm, the choke must be adjusted to allow air to mix with fuel to continue to run.

When the choke isn’t adjusted correctly after the mower warms up, the mower will stop running because it isn’t getting sufficient air flow.

Dirty Spark Plug in a Craftsman Lawn Mower

A dirty or damaged spark plug can cause your mower to run rough or quit running. A dirty spark plug is one that has carbon or oil buildup on the tip. A damaged one is when the porcelain is cracked or the electrodes are burnt.

Check the spark plug(s) in your Craftsman mower and replace it if you find any of a dirty or damaged plug. Make sure the plug is gapped to the engine manufacturer’s specification and that the spark plug wires are securely attached. It is best practice to install new spark plugs annually.

Bad Ignition Coil in a Craftsman Lawn Mower

The ignition coil can be the cause your Craftsman lawn mower won’t stay running. The windings on the ignition coil can separate and short out when the lawn mower gets hot.

This will result in the spark plug not being able to create spark because it is unable to get the voltage it needs. Check for a break in the continuity using an ohm meter.

Bad Battery or Charging System in a Craftsman Lawn Mower

The battery on your lawn mower may be going bad an unable to hold a charge. You may also have a problem with the charging system. Check the cables and terminals and make sure they are secure and free of corrosion. Test the battery to ensure it is holding a charge.

If it does, move on to confirming the charging system is working. Find out how in this guide on checking your battery and the charging system.

Bad Craftsman Fuel Cap

The fuel cap on a Craftsman lawn mower is designed to vent to allow air to pass through the cap. Without this vent, the fuel tank will create a vacuum that will prevent fuel from leaving the fuel tank and getting to the engine. A cap with this problem can run for a bit, but eventually shut down and stop running.

Once the mower has stopped running, remove the fuel cap and start your mower. If it starts and runs fine, you may have a problem with the fuel cap vent. Place the cap back on your fuel tank while allowing your mower to continue to run to see if the mower shuts off after a while to further indicate you have a gas cap problem.

You can attempt to clean the cap and unclog the vent, but this doesn’t always work or may work temporarily. I recommend purchasing a new Craftsman fuel cap.

Craftsman Engine Overheats

When a Craftsman engine overheats, it will shut down and stop running. This could be due to a low engine oil level, wrong type of oil, clogged mower deck and plugged air filter. For additional reasons a Craftsman mower can overheat, check out my guide Things That Can Cause a Lawn Mower to Overheat.

Still Having Problems With Your Craftsman Lawn Mower?

It would be nice to own a mower that will never give you problems. However, they don’t exist. Own a lawn mower long enough you bound to run into problems. The most common of them are problems with starting, smoking, dying, vibrating, and cutting.

I put together a handy guide to help you quickly identify items that can cause a problem in your Craftsman along with ways to solve them. You can find this guide at: Common Craftsman Lawn Mower Problems & Solutions.

If you are unsure how to safely perform diagnostics and repairs on your Craftsman lawn mower, it’s best to have a professional complete the repairs. This will help you avoid personal injury or additional damage to the mower. Your local Craftsman lawn mower dealership or lawn mower repair shop will be able to help you solve your problem.