Small Engine Problem Solving Tips
Small Engine Won’t Start or Runs Poorly
Determine why your small engine won't start by checking your fuel levels, spark plug, carburetor, valve & compression levels and more. Follow along to troubleshoot and learn when it's best to service your engine.
Troubleshoot Your Mower:
Troubleshoot Your Snow Blower:
Stale, untreated gas begins to break down after about a month. Drain the gas from your lawn mower or outdoor power equipment, and then replace with fresh gas and fuel stabilizer to extend the life of your fuel.
Your fuel needs to be stored in a suitable container and treated with fuel stabilizer to be sure it doesn’t go stale. Stale fuel, dirt, and debris are the most common cause of outdoor power equipment not starting or running properly. If you store equipment with untreated gas in the tank, it can lead to engine damage.
Check your oil level and appearance every time you use your engine while it is cold. Your oil typically needs to be changed each season or after every 25 hours of use
- Refer to our Checking and Changing Mower Oil FAQ for further assistance.
Disconnected, dirty or fouled spark plugs are common causes for engines that won’t start. For small engines, spark plugs typically need to be replaced every season or after 25 hours of use.
You should also check to make sure the spark plug gap is set correctly. An improper spark plug gap could lead to engine knocking and poor performance.
- Follow this guide to check and replace your spark plugs.
If your spark plugs look good, problems with your ignition system can also be preventing a spark.
These problems can range from a faulty spark plug lead, shorted kill switch or damage to the flywheel.
- To test and fix possible problems, check out our Small Engine Ignition Systems FAQ.
If the engine is emitting white or blue smoke, this means your engine is burning oil. Check our Engine emits white/blue smoke while running FAQ for assistance.
If the engine in emitting black smoke, this could mean that the air filter is dirty, the fuel could have gone bad, and/or the carburetor is flooded. Start by checking your air filter, if it looks okay, move onto replacing the gas. If the problem continues, refer to the following for cleaning/replacing your Carburetor
Air-fuel compression is crucial to engines powering lawn mowers and outdoor power equipment.
If there isn’t proper valve clearance or there’s a leak, this can cause compression problems that keep an engine from starting. You can perform a compression system with a leak down tester. If you don’t have one of these, we recommend visiting your Briggs & Stratton repair dealer.
WARNING: Always read the engine and equipment manual(s) before starting, operating, or servicing your engine or equipment to avoid personal injury or property damage. See an authorized dealer or contact Briggs & Stratton if you are unsure of any procedure or have additional questions. Find all Engine Safety Warnings