Hi, could these be New Guinea Impatiens?
I don't think they can take 4 hours of hot sun, filtered light or early morning sun might be good for them. Be sure they are moist when you fertilize so the roots don't burn.
They might like a different container with a bit more room for the roots and to grow. One that has good drainage would be good. Karan

I agree with Karan, these are New Guinea impatiens. They should, take that amount of sun when acclimatized. Place them in the shade for a couple of days to see if the 'perk up'. If they don't, prune down to where the second bottom flowers where originally and they should 'rebound'...hopefully! Then, return them to your sunny spot.

Angel, they look wilted , have you let them dry out or kept them too wet? Are the grey spots on the soil the fertilizer that you applied? Before you cut them back get rid of some of that fertilizer if that's what it is. The brown leaves could be from overfertilizing. How long have you had them planted in that pot?