Outdoor Power Equipment

May 2013

Proudly serving the industry for which it was named for more than 50 years, Outdoor Power Equipment provides dealers who sell and service outdoor power equipment with valuable information to succeed in a competitive market.

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• Spark plug: The spark plug is the final element of the ignition chain. High engine efficiency and complete gas combustion are linked to a good spark quality. Generally, we estimate a minimum of 20 millijoules is necessary at the spark plug. Troubleshooting an ignition system today is actually very easy, provided you have the proper test equipment. A lot of us old-timers probably still have a spark tester that looks like a donut with what appears to be a threaded rod with a harp point and a smaller screw that's adjustable. This was a great tool for testing breaker points and early solid state systems. With solid state and CDI systems becoming increasingly reliable, it is extremely important to have a tester than can apply the proper load when testing. Remember, when testing an ignition system outside the engine, you need to compensate for fuel air mixture and the compression ratio. That is why it is extremely important to use the appropriate tester. Almost every manufacturer has a recommended tester that will test the ignition system due to those conditions, and a technician should be aware of that unit. Charging Systems Here is where the smoke really needs to be kept in the wires! Charging systems in today's equipment are really asked to do so much. In the past, all they needed to do was to start the equipment, run an electric clutch, and charge the battery. Today, they are running electric PTOs, charging the battery, running lights, lifting and lowering the cutting heights, and running all the safety switches and safety devices. Some units use the charging system to stop the blades as part of the safety systems, control and/or monitor the fuel systems, run the GPS system — and let's not forget the radio, CD player, and the iPod and gaming systems! All kidding aside, these systems are asked to do so much more; however, the charging systems themselves are not much different than the earlier systems. As stated earlier, the electrical systems may have increased in what is needed of them, but the basic theory for all the system components remains unchanged, and that is a key to troubleshooting them. Alternator Systems All charging systems function according to the same theory. Stators will have a core with two or more posts wound with copper windings. When the south poles align with the stator post, magnetic lines of flux travel through the stator in "one" direction. When the north magnets approach the stator post, the lines of flux travel in the other direction, or simply stated, create Alternating Current (AC). The issue here is that AC can run lights and certain items. However, you also need to create Direct Current (DC) to charge the battery. This is where the fun begins. To create DC, you must take the AC and convert it to DC. This is done by using a diode or a one-way check valve. A full OUTDOOR POWER EQUIPMENT MAY 2013 21

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