Black ink completely disappears after printing a few inches

We have a HP latex 315 printer, while printing the black ink prints for a few inches and then starts to fade as if the printheads are starved of black ink. I printed the 'Printhead Test Plot' and noticed that the black ink was completely missing (cyan is printing properly). I cleaned the CK printheads manually and printed the 'Printhead Test Plot' again and the black ink printed properly but while printing the black disappeared after printing a few inches. I'am not able to figure out if it is a printhead problem or ink supply problem. After cleaning the printheads the test plots don't show any issues but while printing for sometime the black ink disappears. Should I change the printheads or get the ink supply pipes checked for any blockages ?

Hi @sonawane.amit19887822,

From the description, it seems that there is a problem with the black line.

There could be something in the black FI tower or in the tube obstructing the line.

There could also be some air inside the line but I think that if that was the case, the PH would not be recoverable and you mentioned that if you clean the PH you are able to print a bit.

To confirm that the issue is not with the PH itself you could replace it and see if the issue appears again.

In any case, we would recommend the black line be checked for any possible obstruction.