How Things Work How-Spark-Plugs-Work

Published on July 20th, 2016 | by Brandon


How Spark Plugs Work

What is a Spark Plug?

Spark plugs are devices that are responsible for “firing” and causing an explosion in internal combustion engines. All internal combustion engines have spark plugs, as they are a key component in the starting of the engine.


  • Metal
  • Porcelain
  • Insulated Wire

How they Work:

  • A mixture of fuel and air are pulled into the chamber from the carburetor.
  • The spark plug fires at a precise time and ignites the gas mixture when it is at maximum compression in the combustion chamber. This creates the most possible power in each engine cycle.
  • Once the engine is running, the spark plug continues to fire at a specific timing to maintain power.

Maintenance Tips:


Featured Parts:


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2 Responses to How Spark Plugs Work

  1. Esteban Elizondo says:

    Asked to fix a lawnmower. Problem: Won’t start. Briggs & Stratton Engine: Used starting fluid; cleaned air filter and spark plug. Checked for spark by grounding the spark plug and pulling on starter rope [ No visual spark noticed ]. Replaced spark plug; just because it looked old [Gap 0.30]. Replaced magneto. Still not starting or even attempting to start. Tried grounding the spark plug and pulling the cord again to check for visual spark [none seen].
    Puzzled?? Suggestions.

  2. Scott says:

    ignition coil wiring diagram for 5hp Briggs Stratton. Magneto goes to the coil where? it broke from the ignition somewhere. Ignition has spark wire and one other with an eye. Help Please

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