A Craftsman leaf blower operates with an internal combustion engine, so it needs a high voltage spark to ignite the fuel inside the cylinder. The spark also needs to be set off when the fuel is passing through the cylinder. If it is set off too early or too late, the fuel won't ignite and the engine won't start
Change Spark Plug
The spark plug discharges a burst of high voltage electricity. Its electrode gap sits recessed in the cylinder, and a high tension lead wire connects to the other end. The spark is delivered through this wire and attaching boot. Change spark plugs on a seasonal basis at a minimum or more frequently if necessary. Ensure you are using the model of spark plug intended for your Craftsman model leaf blower and that it is securely connected to the rubber boot and the cylinder.
Wiring and Flywheel
The high tension lead wire, which leads back to the ignition module, can become frayed, torn or ripped loose, resulting in a loss of spark. Check the rubber boot and the wire for any damage, following it back to the ignition module. Check the short-circuit and ground wires connected to the ignition module for any loose connections or signs of damage. Follow these wires back to the ignition switch, looking for damage and signs that the wiring is prematurely grounding the circuit. Inspect the ignition switch's connections as well.
Use Ignition Tester
The electrical system on a Craftsman leaf blower must make an entire circuit without experiencing any resistance. A loss of spark could be anywhere in the system, so using an ignition system tester will help determine if the module is at fault or other mechanisms in the ignition system are. These testers hook up to the high tension lead wire's rubber boot and the spark plug. When the starter cord is pulled out, a blue spark should appear in the tester's window. If no spark appears, the problem is likely the ignition module.
Replace Ignition Module
The ignition module contains an electrical coil that acts like a capacitor, storing and discharging the electricity. When this coil loses its efficacy, the voltage of the spark discharged will not be high enough to ignite the fuel in the cylinder. Ignition modules tend to wear out only after many seasons of work, so you can rule out all other sources of electrical failure before replacing the ignition module. This repair involves dangerous levels of electricity, so leave the job to a professional if you're not confident making the repairs.