Small Engine Repair: How to Check for Spark on a Tecumseh, Honda, Briggs & Stratton Lawn Mower



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**Always follow the instructions in your repair manual when doing repair or maintenance work on Outdoor Power Equipment. Manuals can be found at the manufacturers website.**

Most people check for proper engine spark by removing the spark plug, attaching the plug wire and grounding the plug to the engine while spinning the engine over and looking for a spark to jump across the spark plug gap. This method is not always reliable. The amount of voltage needed to jump the spark gap set at .030″ with the plug removed from the engine is about 2000 volts. The amount of voltage required to jump the same plug gap with the plug installed in the engine and operating under operating conditions is about 8000 volts, so it is possible to see a spark with the plug removed, but not have a spark with the plug installed.

A more reliable method is to remove the spark plug wire cap, and hold the spark plug wire approximately 3/16″ away from the spark plug and spin the engine over. A good ignition system will produce a orange/blue spark from the end of the spark plug wire to the spark plug. The problem with this method is it is easy to get shocked and hard to turn the engine over while trying to hold the end of the plug wire 3/16″ away from the plug. The benefit of this method is it is more reliable then the first method and doesn’t require purchasing any special tools.

Another method for checking the ignition for proper spark is to purchase the Briggs & Stratton Spark Tester, part #19368. This tool can be used to check for spark with the plug removed and using no hands, so the engine is easy to spin over and there is no risk of being shocked. The tool can also be used to view the spark while the engine is running. This is very valuable when trying to diagnose a rough running engine or a engine with intermittent problems.

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26 Replies to “Small Engine Repair: How to Check for Spark on a Tecumseh, Honda, Briggs & Stratton Lawn Mower”

  1. Engine stalls when hot. I used this tool inline when the engine is restarted, however I do not see the arc between the electrodes, while the engine is running. Could this indicate a weak coil when it's hot? -Rick

  2. HELP ME PLEASE ok so i was trying to get this lawnmower started for a guy and i took the cap off and it took it off the wires please help i dont want to get yelled at and have to pay for another one its also a tecumseh though its a 6.5 hp

  3. You need to check the kill circuit as well, the small wire hooked to the coil, sometimes if the circuit is closed it will not let the coil fire.  Sometimes that wire will be grounded to the engine

  4. I enjoy your videos. Great Job!

    I have the briggs spark tester. However, I find it challenging to pull the cord and watch for spark at the same time. Depending on the mower, the tester is often at the front of the mower. Even if I can get the tester in a position where I can see it, there is often glare on the plexiglass windows. Any tips or suggestions? Are there other testers that are easier to see and have a longer lead? Thanks!

  5. New lawnmowers with mandated safety requirements will not have spark present unless the mechanical safety handle is pulled down to remove the spark to ground(an intended spark killer) and activate the blade clutch. Without the safety override, you'll never get spark.

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