To test the coil to determine that it is bad, unhook the switch wire from coil to switch, install a spark tester between the spark plug boot and plug, pull the rope, if you have spark coil is good, if no spark check the ground wire from the coil to the cylinder block, that wire that goes to cylinder block is usually green in color. The reason behind that is the coil bolts to the plastic crankcase and the coil has to be grounded to work, so a ground wire runs from the coil to the block to complete the circuit. .
- Spark ignition tester suitable for just about all chainsaws, trimmers and blowers
- hook to spark plug wire and spark plug and pull rope, you can see spark if ignition system is good
- if no spark then saw would need repairs