Just purchased a used Southern Yankee 4' 6 rack rotisserie trailer mounted smoker. This model came with a BBQ Guru Competitor and 25cfm fan. I set the pit control to 225° and had the pit probe mounted just inside the door. I also checked the temp with a thermapen through a hole drilled in the pit about 3/4 way up the side close to the edge an it usually read in the 240°. After 4 hours of smoke the butt was in the 115° range. I usually wrap at 4-5 hours with a temp of 155°. At the 11 hour mark I was only at about 165°. I brought the butt in and finished it in the oven. I was using lump charcoal for my fuel with some hickory chunks for smoke. What am i doing wrong? Does the volume of wood/charcoal factor in? Should the BBQ Guru just be set at a higher temp? Is it normal to burn up 40lbs of lump charcoal in 12 hours? Also the attached warming box never got any warmer than 110°.