I have a lexmark s315 every time i print a picture out the colors are faint and there are yellow lines threw the picture why?

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That's normal. The printer when left on power saver mode will perform a maintenance on the cartridges to prevent it from drying.

Sounds like you just need a new printer. Some times the encoder wheel can get dirty with aerosolized ink and it will start to skip lines. The encoder wheel is a small plastic wheel on the paper feed of your printer. Around the edge of the wheel are hundreds of small thin black lines. As paper goes through the printer it counts these lines as the wheel turns to know how far to push the paper. If ink or debris gets between the lines over time it can start counting two lines as one and thus advance the paper too far, causing blank space between prints. See the below picture of a printer encoder wheel for reference. My professional opinion is to not purchase Lexmark. New Canon printers are very reliable with a high quality output, look for one that uses CLI-221 cartridges. Or most any HP.

from cnet review of the product

• Unfortunately, as with the Z1420, fast print speeds come at the cost of print quality with the Z1300. Black text prints, though nicely dark, were beset by obvious jaggedness. The color graphics print had a slightly faded look to it and color blocks showed graininess and faint horizontal striations. Barcode-style patterns were muddled, too. For our tests, we printed color 4x6 photos with the standard black and tricolor cartridges, as Lexmark did not include photo ink tanks with the test unit. The colors were dull, details were hazy, and again, the entire print was marred by graininess and faint horizontal lines. That said, nobody buys a $25 printer to print photos for framing or to create displays for a classroom science project. A $25 printer is a convenience item for occasional reference prints, and as such, the Z1300 does its job.

Inkjet printer quality
(Longer bars indicate better performance)
Photo Graphics Text Canon Pixma iP1800
Good Good Good Lexmark Z1300
Fair Fair Fair Lexmark Z1420
Fair Fair Fair

have you tried printing alignment page after you installed a new ink or cartridges if you did not try to print an alignment page first

replace all ink cartridges.

try doing another alignment page ...

Threw it in the garbage and ordered another, just saved the ink cartridges.

This is the problem with the cartridge if you brought original Lexmark cartridge you can get it exchanged as the cartridge is nay be defective and the cartridge comes with one year warranty...........................................

Your post "...it prints very faint horizontal lines in color..." is indicative that indeed your color printheads are clogged and would need repetitive deep head cleaning. This is of course would require that you keep on cleaning until such time as the faint color lines have turned to legible print.