Small Engine Service | Engine won't start

Common Engine Troubleshooting

Use this help guide to help understand and troubleshoot:

  1. Why an engine will not start 
  2. Why an engine is smoking
  3. Why an engine is over-heating. 

If this is your first time starting the engine, please contact our customer support for assistance at (888) 896-6881 or create a ticket for help and warranty support.  

Caution:  Disconnect the spark plug before performing engine repair.  Engine should be cool, especially when checking or adding fuel.  Follow owner's manual safety instructions.


Most common reasons why an engine will not start is a fuel related issues.  Gasoline fuel can spoil over time, and if spoiled fuel is left in the fuel tank, it will certainly cause issues in the carburetor and engine start up.

1.  Check fuel level

  • If empty then fill up.
  • If fuel is present, then check if fuel shut-off valve is open.
  • If fuel is stale, dirty, or has been stored with untread gas it can lead to engine damage.  A fuel stabilizer will keep the gasoline from creating small engine problems.

2.  Clean the carburetor

  • The carburetor regulates how air and fuel move through the engine to power your equipment.  If the carburetor is dirty, that can cause poor engine performance or starting problems.  The issue is a result of clog fuel and air passages.
  • Check the air filter.  Make sure that the air coming into the carburetor is clean and free of debris by inspecting the air filter.  A clogged air filter is a common cause for black smoke emitting from the exhaust.
  • Check the linkages.  Linkages attached to the carburetor's throttle and choke plates can bind or stick when dirty.  
  • Use carburetor cleaner to remove deposits, clogs & debris.
  • If further action is necessary, look into a carburetor rebuild, overhaul, or replacement.
  • Avoid problems by performing annual tune-up with a small engine tune-up kit.
3.  Check the spark plug 
  • Disconnected, dirty, or fouled spark plugs are common causes for engines that won't start.  Spark plugs typically need to be replaced every season or 25 hours of use.  
  • Check that the spark plug gap is set properly.  Use a spark plug gap chart to find the right replacement & setting.  Typical spark plug gap is .030”.

4.  Low-Oil Sensor 

If your engine is equipped with a low-oil sensor, it could be preventing the engine from starting.  To test this, disconnect the sensor and try to start the engine.  If it does start, you can use the equipment as long as you monitor the oil level before use until you have a chance to replace the sensor.  The external sensor is easy to replace and is the more likely unit to fail.  If the internal level and sensor has failed, it would be more difficult to repair.

Want to watch some video for common engine repairs?
     Click Here:  Watch Service Mechanic gurus repair engines on our YouTube


1.  Is the air filter dirty or plugged? 

  • Clean the filter.
2.  Is the engine emitting white / blue smoke? 
  • Engine is burning oil.
3.  Is the engine emitting black smoke?
  • Needs a carburetor adjustment.


1.  Is the engine dirty?

  • Clean and remove debris from the engine.
2.  Check the oil
  • Never add oil to the gasoline for a four-stroke engine.
3.  Is the fuel mixture too lean?
  • Determine if the air-fuel mixture is off by check the state of the carburetor.

Man working on engine in his home garage.

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