First, what variety of basil? If you're talking sweet or genovese, they should be a deeper green, but lots of the other varietals like lemon are paler. Generally, yellowing leaves are a sign of either nitrogen deficiency, but you said you fertilized so I'm doubting that, or overwatering. Does the raised planter drain? Basil does like lots of water, but not drowning. Maybe try letting the soil dry just until they droop a bit, then water?

I bet it is overwatering. Thank you. I cannot believe I did not think of that, and yet again, I can. it has been one of those weeks. My irrigation clock had a hiccup. I had to unplug it a reprogram everything.