Weed eater starts then dies when i let off the gas?

If there is an idle mixture adjustment, try that. It shouldn't be belching smoke, but it should be rich enough so there is not excessive throttle lag when you pull the trigger. I had this problem with mine, so the carb apart, cleaned it, and also cleaned all the carbon out of the combustion chamber.

You could also have this problem if the engine has very low compression. It will run fine at WOT (with reduced power), but it won't idle very well with all the leakage.

Look at the carb youll see two set screws that go into the carb the one closest to the motor is the idle adjust get the motor running and adjust it either way untill it stays runnin

I'm going with the carburetor as well. But check the fuel mix as well.

The carburetor either needs adjusting or it needs to be cleaned and rebuilt.

Run it in half choke.

heater has problem