Fuel restriction within the carb . You will have to clean the fuel circuits carefully with a tag wire and compressed air and add some fuel cleaner to your fresh fuel and use a stabilizer in the future when ever you store your unit .

ewalk has it right. I've had several of these. The things I do is take the gas tank off and clean it, clean the carb with carb cleaner, replace the fuel lines with new ones - good to go. I usually run the gas completely out of the carb before storing.

I have a craftsman 27cc speed start - date of 2012. It idles great a low speed - high speed not so much. I don't have the model - sticker is erased. Was wondering what carb in in this thing - and looking for a carb jet tool that fits this trimmer.