If there is no spark reaching your leaf blower's spark plug there's a good chance it's time to replace the ignition coil. The ignition coil generates electricity, or spark, so that the spark plug can cause combustion in the cylinder. When the coil breaks down, the leaf blower will no longer start.
Set the leaf blower on a flat work bench.
Remove the ignition switch located on the side of the engine with a Phillips screwdriver. Pull out the connectors that go into the switch.
Install the jumper wire by placing both ends of the wire into the open connectors that were removed from the ignition switch. This will bypass the circuit to ensure proper testing of the coil.
Remove the spark plug wire from the spark plug. Plug the spark tester into the boot of the spark plug wire. Clip the other lead of the tester to the end of the spark plug.
Pull the starter cord rapidly while watching the tester. If a strong blue spark is present the coil is fine. If there is a weak spark or the spark is not present, the coil needs replacement.