Start but will not run for long and when it's running it quits when it gets hot.

Are you adding the 2-cycle oil to gas?

Hi,
Will not run long is either a clogged inlet screen or pump diapragm, commonly. Dies when hot is usually ignition.
Peace,
Clarke

It depends how old it is newer models have a high and low adjustment for carb older models have just one .New ones have two round adjustment knobs. High on right low on left. Use red wire connector on scratch awlthese work great. Sounds like you need to advance knob on right clockwise. You tube adjusting weedwackers without factory carb adjusteralso adjusting weedeater.