My i850 printer has not been used for several years. I just tried to use it on a MacPro running OSX 10.5. It will not print black text but does print black test patterns (though often with vertical lines). Yellow test patterns are very weak. I have run the deep cleaning routine a couple of times and replaced all the ink cartridges to no effect. What next?

When you print photos you print in Max dpi, for this no faded lines anywhere. Probably you have a problem only in black color in print head.
Мay be it's partially clogged or partially defective.

Please try to uninstall and reinstall your printer.

Clean your printer heads.

Perform a hard reset to your printer.

Print a test page.

Try using a different bond paper.

Make sure you are using original canon cartridge

If still you get an error. Replace your printer heads.

try to check if you are using 2 ink cartridges. it might be that you are using just one cartridge color. :)

Try it this way...Uninstall the drivers once again, disconnect the printer from the computer. Download and install the new printers and do not connect the printer until instructed to do so. Run the installation and when the printer is connected and drivers are installed...reboot again and give it a try...You did select the proper drivers for XP or Vista whatever your operating system: http://www.usa.canon.com/consumer/controller?act=ModelInfoAct&tabact=SupportDetailTabAct&fcategoryid=232&modelid=8047#DownloadDetailAct
there is also some update software on this page this also might help make things run a little better. If you are not using XP back up one page and select Vista
Good luck, please leave rating..thank you

Assuming genuine ink cartThis worked for me on a HP printer 1.Try print black text ,and run many copies black only. I ran 25x12 times still no black. Run head clean after about each 50 sheets. Persevered and finally BLACK ink OK
Good Luck Inkypete

Sounds like your black pigment (PGBK-5) cartridge has clogged up the printhead or similar.

You could try running a single Deep clean on the that colour alone (use Right click printer > printing preferences > maintenance tab > Deep Cleaning)

If that doesn't work you will probably need to either:
- clean the printhead (see this thread)
or
- replace the printhead/cartridge

Hope that helps.

thats tuff did cannon.com have it or mac website of not not made for u i know im sorry

try running your maintenance program.
go to your printer settings
right click on canon i850
left click on properties
run cleaning or deep cleaning,
then print head alignment and/or nozzle check

Chewbacca08's solution gave me an idea. I set the print setting to photos paper (even though I was trying to print on plain paper) and IT WORKED. It's worth a shot before you trash a perfectly good printer.

I would try to replace the printhead and the magenta cartridge at the same time. Lots of people with leaky cartridges have this same symptom only, it is with whatever color is malfunctioning.