Canon Carts Not Printing?
(from a post in printerhelp)

Here are some possible solutions.There may be dust in the cable connections, disconnect the cable and blow out the connectors. To print a test pattern at the printer, press and hold the power button until it beeps 4 times and release. It should print a small spray pattern going from yellow to blue to red then black. If that doesn't help make sure the the lever on the print cartridge is in the center position and that you have removed all the protective tape from both the tanks and printhead. After closing up the printer (be sure to press green button inside printer to return printhead to ready position) press and hold the resume button until it beeps once. This puts printer in printhead clean mode. It takes 5-10 seconds before it's done.