How Can I Fix My HP Envy 4520 Not Printing Black Ink Properly?

It is very frustrating that my HP 4520 printer not printing black ink correctly. It is printing very blurry or grey. I have examined the ink level of the black color cartridges, and it is three-fourths filled. Sometimes it prints the blank pages. I do not know why my printer not printing well. Even I have updated Windows and all the printer drivers and software. I must say, we are using genuine HP cartridges. Please help me with some troubleshooting guides to fix this printing issue.
Response By- [Kelvin Morton]
Hello there, thanks for your query. This issue is fixable in most of the cases. This 4520 printer not printing error occurs because of bogus ink cartridges, dirty printheads, empty cartridges, improper paper settings, and outdated firmware. You just have to follow the guide from our article post to resolve HP printer not printing black ink. Make sure you follow the steps carefully.