It's getting around 6-7 hours of direct sunlight everyday. Right now the temperature is in the range of 36-38 ºC (97-100 ºF) and expected to go till 40ºC (104ºF). Is the weather too hot for this plant?
If you are feeding it lots of fertilizer, you might want to hold off on that as well as excessive watering. I had 2 Kiwanos last year, one in beautiful, composted soil that I watered and fertilized regularly and another that I planted in poor soil that I did not water like I probably should have, even in the extreme heat. Never fertilized it either.
The one that I cared for, grew up a trellis and was huge, green and beautiful but only produced 2 small fruits. The one that I neglected was yellowed, ugly and growing along the ground. I didn't even realize how many fruits it had until I pulled back the grass, and it had over 20 melons!