This model printer uses one tri-color ink cart to print both color and black. In order to print black it must mix all 3 colors equally. When the print head nozzes of one or two of the colors are slightly clogged it makes various colors of black.

Try this.

When you don't use your ink carts for a while, when you get new ink carts that have been stored in warehouses for a number of months, or when you have refilled a slightly too dry ink cart, the print head nozzles on the bottom of the ink carts get clogged with dried ink. The printer head cleaner menu will NOT dissolve the dried ink. Water will. Try this. Soak the bottom of the clogged ink cart in 1/2 inch of hot water for 15-30 minutes. Blot dry with clean paper towel (you should see the 3 ink colors on the towel). Retry.