Why won't my Husqvarna 150 BT blower shut off? It starts and runs great, but won't kill with the switch.

most likely a bad earth or faulty switch, check the wiring from the switch to the ignition module.
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The blower will need to be checked to see what is wrong. Start with compression, should be 125-145 lbs/in Check spark with a spark tester and make sure to use resistor plug. Next, make sure the fuel lines are in good condition and not cracked or leaking. If the unit has set with fuel in the unit, chances are the carburetor is clogged and the fuel lines are damaged.

Pull the muffler and look for scoring on the piston. I think you cooked it my friend. You may have a bad coil or fuel cap, but it's more likely you ran the mix too lean.

Sounds like a fuel starvation problem, Strip and clean carb. Avoid using airlines to clean carbs. remove low and high adjustment screws, reset to factory settings. Walbro carbs are generally scew both of them back in all the way and then turn out 2 full turns each anticlockwise.

Do you have good compression, good spark and is fuel getting into the cylinder.? More information would help diagnose the problem.

sounds like your kill/shut off switch is bad grounding it out. Unhook the small wire from the coil and see if you have spark then, if you do then the problem is the switch or safety switch and or possibly the wires that run to the switch .

I had the same issue with a Husqvarna 150 BT blower. Brand new ran through 2 tanks of gas and need to buy more gas , mixed 50 to 1 ratio 87 octane on new gas which was the same as what i was running and it started pinging and running like **** then stalled and would not start. took the plug out and it was fouled. cleaned the plug got it running again but still not good. This model comes with a NGK CMS7H plug which i replaced with a champion RZ7C and new gas 93 octane and lawnboy oil mixed 50 to 1 ration and now its running like a champ. I've had bad experiences with NGK spark plugs in the past and thought this may resolve the issue and it did. Hope this is helpful to anyone out there having the same issues. Also used some fuel stabilizer in the fuel mix, I hear this helps with the ethanol problem in the fall/winter gas.