Lifting in the morning just not working for me

I've been trying to have a split schedule with cardio in the morning and lifting at night when it's in my schedule, but in the last few Weeks due to the holidays and vacation I've done both in the morning when limited to time.  I always do weights then cardio, but when I get to my fifth our sixth sets in each exercise, I fall flat on energy.  Normally in the evening I have much more energy and this would be because of me fueling with food all day.
The last time I did BFL I did most of my workouts in the morning, this worked for me.  It's probably more of an expectation thing now then back then, not realizing that with more fuel, I could lift more, but sure made me feel bummed a little this time around.  Moral of story, food equals energy to help push harder through the reps, but my goal is fat burning so I need not worry about as much on strength in my morning workouts, just stick with the program and rest between sets :)