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Do It Yourself - Outdoor Power Equipment Repair & Maintenance

How to Service Your Spark Plugs

How to Service Spark Plugs Posted in Small Engines

Spark plugs are a very important part of the internal combustion engine and need to be kept in good condition to allow for optimal performance. The electrodes of the spark plug need to be kept clean and sharp to create the powerful spark necessary for ignition.

A damaged or dirty spark plug can lead to inconsistent firing which can result in reduced or inconsistent performance. It can also cause an excess of fuel consumption and result in deposits being left on the cylinder head.

The good thing is, spark plugs are easy to repair, maintain, and if necessary, replace. We will explore the steps to inspect and service your spark plugs. With this information, you can then decide whether or not you want to replace your spark plugs.

Inspecting and Cleaning a Spark Plug

  1. Start by disconnecting the spark plug lead from the spark plug. Remove any debris around the spark plug before you remove the plug to keep the debris from getting into the combustion chamber.
  2. Remove the spark plug by using a spark plug socket wrench.
  3. Using a wire brush and spray on plug cleaner, remove light deposits from the plug. If there are still difficult deposits, try using a strong knife to scrape them off. DO NOT use a shot blaster or abrasives to clean your spark plug.
  4. Inspect your spark plug for damage and heavy deposits. If there is any damage, you should replace your spark plug. Refer to our guide on How to Read a Spark Plug to help you determine any issues with your spark plug.
  5. Next, check the gap between the electrodes at the tip of the spark plug by using a spark plug gauge. A typical gap for small engine plugs is 0.030". But, you should always check the specifications for your particular model to be sure.

    Spark Plug Gap Note: Too small of a gap could result in a smaller and weaker spark, leading to an increase in fuel consumption. Too large of a gap could result in misfiring or premature electrode wear.
  6. Finally, reinstall your spark plug and attach the spark plug lead. Be sure not to overtighten your spark plug when you reinstall it.

If you've done all this and still have problems you may want to use a spark plug tester to diagnose whether you have a problem with your ignition system or you are having a spark plug misfire. If you have a spark plug that is misfiring, you should replace your spark plug. Check out our selection of spark plugs here at Jack's.


Jack's Safety Tips: Before servicing or repairing any power equipment, disconnect the spark plug and battery cables. Remember to wear appropriate safety glasses and gloves to protect against harmful chemicals and debris. View our Disclaimer.