hi everyone. i have an 07 ranger xp. the question i have is than when i'm drive down a snow covered or ice covered road i like to keep it in 4 wheel drive. at 30mph it disengages and the back tires will break free and start to slide all over the place. is this normal or is there something i can change to prevent it from happening?

i have an 07 ranger xp. having problems with tps  and fuel system. service manual says fuel pump should start when key is on. it will only run when starting or runing. is this a problem? Also i'm getting a reading of 44 psi at an idle then it goes up to 46 to 47 psi when engine is reved up. should i be relacing the pump?