As others have already stated, the problem you ran into is called "the stall." I don't think anyone mentioned why it happens. This will be a good thing for you to know because, in the future, you can take action to overcome the problem so you can get your food on the table at a reasonable time. You just have to know what you are trading off when you do one or more of the things I am about to describe.
The stall is caused by the meat sweating. As the moisture in the meat comes out from the meat getting hotter, it evaporates from the surface. This evaporation cools the meat, just like what happens when any of us sweat. With a really big hunk of meat, you often end up with a long period of equilibrium where the heat going into the meat is exactly offset by the cooling from evaporation. This can go on for hours: I've had it go on for over four hours with an eight pound pork butt, and during that time, the temperature did not go up even one degree.
If you are spraying the meat with apple juice (or anything else), that will put more moisture on the surface, and increase the evaporation, thus making the stall last longer.
No that you understand why it happens, here is what you can do about it.
Increase the smoker temperature. From what I have read in these forums, as well as my brief (18 months) experience, 225 is too low a temperature for a pork butt. Most people seem to use 250, or even a little higher. You don't want to go too high because one of the reasons smoked pork butt is the king of BBQ is the delicious taste you get from the juices that render out of the fat. To get that taste, you need to smoke for a long time. So, my recommendation is to smoke at 250, but no higher, even though others seem to have success with much higher temps.
Decrease the spritzing. Most pulled pork recipes call for spraying some sort of sugar water on the pork about once an hour. This is supposed to help build up the desirable "bark" which is loaded with flavor. However, it also cools down the meat quite a bit and, with an electric smoker, it may take 5-10 minutes for the smoker temperature to return to 250 after you open the door to spray the meat, so you lose a little bit of time there (not much compared to everything else). I don't like to decrease the number of times I spray, but if I were in a hurry, I'd stop the spraying.
Don't inject. I have never injected any of my meats, so I have no idea what I'm missing. However, I am pretty sure that the extra moisture will increase the amount of evaporative cooling. One person recently posted that he got a stall on a chicken smoke, something I didn't think was possible with such a relatively small piece of "meat." However, it turns out he had injected it, and I suspect that was the reason he got a stall.
Foil it. This is the tried-and-true stall killer. A lot of people in these forums don't like to do it, and as a result, they have a somewhat negative phrase for it: "the crutch." I think some people think it is cheating. However, it works every time, and will get you "home" in a jiffy. It should be obvious why this works: the moisture coming out of the meat can no longer evaporate. This completely and totally stops the evaporative cooling and, since the heat from the oven can instantly penetrate the foil (aluminum is a great conductor of heat), the meat must heat up.
I did another pulled pork two days ago. I always take notes (I suggest you do this as well) so I can time my next meal more accurately. I somewhat disagree with others who say you can't get the food on the table when you want, but you do have to make some compromises. For this last pulled pork smoke I used my external smoking can attached to my MES 30, with the
AMNPS tray lit at both ends. The smoker was set at 245 degrees until I foiled, at which point I bumped it up to max (275). I didn't want to increase the temperature that much, but we needed to eat (I was late getting started and didn't get the pork in the smoker until almost 9:00 a.m . -- try not to start that late).
Time Temperature
0:00 40
1:23 70
2:00 86
3:35 118
5:04 138
6:00 145
7:00 151
8:15 151 (foiled and put smoker at 275)
9:30 192
9:50 201 (pulled)
BTW, note that my times are referenced to 0:00, rather than a time of day. I have a count-up timer and always start that at a beginning of a smoke. I find this incredibly useful because I always instantly know how long the smoke is taking, and I can refer to my notes from earlier smokes to see what to expect next. If you start with more or less that same cut of meat, butchered in the same manner, it has been my experience that the process is somewhat predictable, although there are always variations. As others have said, you should always cook to get the meat to a specific temperature rather than simply cook it for a specific time.
You can see the stall starting to happen about five hours into the smoke, and at seven hours it is has become a full-throated stall. At 8:15 I put the pork in the disposable pan that I put on the rack underneath. It was full of all the drippings. I then put thick foil over the top and sealed it well. As you can see, the temperature started shooting up almost immediately (actually, it took ten minutes before the temp went from 151 to 152, but it rose rapidly after that).
I have one more pork butt (Costco sells them two at a time). When I do the next one, I will start it at 5:00 a.m., not 9:00. I will definitely light both ends of the
AMNPS, just as I did this time. I will still spritz, but I may do it every two hours rather than every hour, because the moisture didn't seem to fully evaporate between spritzes. I will still use 245 degrees as the smoking temperature, although I might go up to 250, since that seems to be a temperature commonly recommended in these forums and, as you are finding out, these people know what they are doing.
This was my third pulled pork. The first one took 12:15 until I took it out, plus two hours in the cooler. That was before I knew any of what I just wrote. My second one took thirteen hours. I knew everything before I did that one, but really wanted to see if I could beat the stall without the foiling, but after eleven hours I got hungry and foiled it.
Now that I have the
AMNPS and an external "mailbox mod" I am tempted to start the next one at midnight, let it go for 14-15 hours, and then let it sit in the cooler until we feel like eating. I still want to see if I can do at least one without any foiling.
Oh yes, if you do foil, you don't need to keep adding smoke because the foil block any of it from getting to the meat. Depending on your smoker it can save both time and money by not wasting wood chips.