Husqvarna model 125b Hand held blower (Gas) No

Either the return line to the tank from the primer has a hole in it, is broke, disconnected; or the diaphragms in the carb are stiff and the unit is flooding

Is the gas fresh or old that you used. Since this brand new, it's under warranty. If you've had it for a few days, return to the store from which purchased it. It should run right out of the box without having to work on it.

Remove plug, leave plug wire on plug wrap a piece of conducting wire around the plug base and other end of wire wrap around metal part of engine pull starter and see if you have spark. You may have to darken area to see spark. If you have no spark probably bad coil or could be just switch has gone bad.

how does it run with out the air filter in place? maybe its plugged and need's replacement

I have a Husqvarna 125B same problem. Turned out to be a bad gas cap. Doesn't vent properly and starves the engine. I took the gas cap off of my Huqvarna weed eater and put on blower and blower worked fine,

the rule of thumb is spark, fuel, compression. I found I gad a plugged air filter. It would not start until I removed it and tried to start.

Yes, but if you use 50:1, it may smoke just a little.

husqvarna model 125b weed trimmer what spark plug do i use manual says rcj-6y in technical data and rcj-8y in monthly maint. ????

Maybe you have some problem with the carburator. You can put some gas in the carb if it start and then turn out your problem was the carb.

Here is a Link to one of my Tips:

http://www.fixya.com/support/r6081405-cleaning_small_engie_carburetor

Good Luck!

Jim