Chainsaw: Check spark plug - this is how it works

If the chain saw does not run smoothly, there are many reasons. In many cases, the spark plug is to blame. How to check them, and what the test result reveals, you can read in detail in this post.

Testing the spark plug

At startup problems, the spark plug and air filter tests are the first two things you usually do. What you can do afterwards, read in this post.

When testing the spark plug, proceed as follows:

Candle wet or dry?

The candle is first checked to see if it is wet or dry. With a dry candle, the fault is not with the spark plug, but with the fuel supply. The spark plug then does not need to be tested further.

Spark present or not available?

If the candle is wet, you must continue to search in the area of ​​the ignition. If there is a spark, the fault is in the air supply (possibly air filter too dirty). If no Zünfunke available, the error and the cause of the startup problems actually at the ignition.

Replacement of the spark plug is indicated in this case. Of course, should the spark plug become sooty or worn, it should also be replaced.

Other problems with the spark plug

  • Spark plug sooty
  • Oiled spark plug
  • Spark plug overheated

Sooty spark plugs are mainly caused by too rich mixtures. The electrode gap may also be too large, or a mismatched spark plug may be used.

A oily spark plug is a sign that there is too much oil in the fuel. Check the mixing ratio (usually 1:25 or 1:50).

On the one hand, a superheated spark plug can be a sign that the spark plug is loose, but also that the mixture used is too lean. Check mixture and tighten spark plug.

Tips & Tricks

Spark plugs are always wearing parts and should be regularly maintained and always replaced in good time to avoid problems in advance. To remove the spark plug you need a matching key - here are different sizes common, pay attention to it when choosing the key on it.

Video Board: How to Checking for Spark on Stihl Chainsaw Using Spark Plug and Scrench in the field.