I've got a echo pb603 backpack blower and a pas260, (both brand new this year). They start-up and idle with no problems. When i go to give them gas they will die out, I have to start and restart them at least 4-5 times b4 they will stay running. What could be the prob. Wrong oil/gas mixture? But i think i have that right, I put the one little bottle of echo 2 cycle with 2 gallons of gas like itsays, What could this be???