My tractor wouldn't start. So i jump sarted it with my van. I attached cables jumped on tractor and started right up. I detached cables put c85 in gear and a minute later backfires and quits. Checked oil gear oil gas all good. Battery reads 10.8 voltz. repeated this process 4 times to drive c85 back to my garage. Anyone had this before. Oh and its a new battery last year. I looked for a short or loose connection and didn't find anything???