All of the water, fertilizer, etc., in the world won't help these plants out there in full sun. They need a little shade.
Now, don't get me wrong. Sago palms can take the heat. They can live in full sun. But they flourish with a little shade. Drive around your neighborhood and look at the ones that are doing well. They're usually tucked up a bit under overhangs, or they are facing east (and only getting morning sun), or nearby a tree that gives dappled shade, which is the best for them.
The sago palm pictured is in Encanto Park in Phoenix, and it's gotta be over eighty years old. It's planted in grass, and in full sun, neither of which is really good for the plant. But it survives! Unfortunately, that's all it does. The leaves don't have that full, green, lush look of a plant that has been grown in a little shade, without the competition of Bermuda grass. Hopefully, your sago palm isn't quite this big. If it is, then it would be way too heavy to move. If it isn't, find a place with a little bit of shade, and it will look a whole lot better!