It should go without saying that having the right tools to work on lawn mower equipment is a major aspect of any job.
Most of what you need is an assortment of common hand tools that are usually already available around the average home or workshop.
I’ve listed below a few specialty tools that you should have access to in addition to your common hand tools. Most of these are relatively inexpensive and can be used for more than troubleshooting small engines and lawn mowers.

Spark Tester  
 
Although it is possible to work without one, a commercial spark tester is a “must have” tool when it comes to serious equipment troubleshooting. With a specially calibrated or adjustable air gap, these tools make short work out of testing lawn mower ignition systems.

Squirt Bottle

Now, here’s a really high tech tool!

I can’t imagine working without this handy little jewel. This makes for an easy way to keep a couple of ounces of fresh fuel close at hand for use when testing a suspected fuel or carb problem in the mower.

With a short length of small diameter fuel hose attached, it’s easy to prime the combustion chamber or throat of the carb with a little shot of fuel.

Mine happens to be a 4 ounce bottle, but something a little larger or smaller works just fine.

Keep in mind that gasoline is HIGHLY FLAMMABLE in any quantity, so be sure to take appropriate safety precautions.  

Tachometer

The tachometer is used to check and or adjust the lawn mower engine RPM.

I use a dual purpose “inductive style” digital tachometer made by Tiny-Tach that also serves as an hour meter. 

It can be used as a hand held test meter or if you prefer, surface mounted on the engine or equipment as a permanent installation.

Tips for successful troubleshooting:

  • Keep it simple! Always check the easier things first, working towards the more complex!
  • Never assume that a system or component is working properly. Verify it!
  • Check only one area at a time and don’t move on to something else until you’ve eliminated the system or component as the cause for your problem.
  • If you become frustrated, take a breather and walk away from the problem for a while. Don’t allow your emotion to control your logic.
  • When in doubt, always refer to the proper repair instruction manuals for information and guidance.

Multi-tester

The multi-tester is used to check both circuits and individual electrical components of equipment.

I like an inductive style digital meter with auto ranging features. They also come in analog versions. Whatever type you use, it should be capable of performing the following types of measurements and tests:

AC-DC Voltage
AC-DC Amperage
Resistance/Ohms/Continuity
Diode Testing

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Jumper Leads

An assortment of colored jumper leads are useful when testing the electrical system or components. They make it much easier to test otherwise hard to reach areas.

Continuity Tester

The continuity tester is an indispensable tool used to quick check electrical power circuits.

With the clamp attached to a good engine or chassis ground, the sharp probe is used to test various connections. The bulb in the handle lights up any time a 12 volt supply is present.

These tools will make working on your lawn mower and other power equipment much easier. Remember, have the right tool for the job!