Help with burn back on thick metal

by Jon
(MA)

Your site is great. I really appreciate all the great information. I have a Hobart Handler 210 and it has been great so far. Welding exhaust and up to say 1/8" i have no problem at all. It does everything i want it to. When i move up to thicker metal that requires multiple passes, and i have to turn the power up I have no luck at all. I have tried absolutely everything power and wire speed wise as well as stick-out, angle, and travel speed. I have also tried changing wire size with no luck. I am able to get it sounding just right and get the puddle moving as i want it to and then it burns back every time in a matter of seconds and welds the wire to the contact tip. It is really frustrating for me. I have nobody around to teach me first hand so at this point i feel like i am stuck. I have been able to teach myself up until now with the help of your site. I run 75/25 at 20cfh or whatever the flow-rate measurement is called by the way.
I'll attach a photo just to show that it welds thinner stuff just fine. I have only just started so i am not very skilled yet.
Thank you for your time. Greatly appreciate all the help from this site.