Answer: Good grief! It sounds as though you are doing everything you can to solve the problem. As long as grass has plenty of sunshine and water and it is planted in well draining soil, it should grow lush and green. Since you've added top soil, the soil should not be the problem. That narrows it down to adequate watering and being careful not to overfeed. Lawns need at least one inch of water per week. You might want to check to see how much water your sprinklers are actually putting out. Place several empty cat food or tuna cans on the lawn and water as you normally do. When you're finished check the amount of water in each can. If it doesn't equal an inch, you're not applying enough water. If the water runs off the lawn before you've applied one inch, break your watering down into 15 minute increments, to allow the water to soak in. Turn the sprinklers on for 15 minutes, off for 15 minutes, on and off again, etc.
As for feeding, be sure you're not over applying the food. Too much nitrogen can burn the roots and kill the grass.
I sure hope this information will help you grow a healthy lawn!
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