Didn't your printer indicate that it was out of the color inks?
You need to either buy some Canon cartridges (wow, for that price you could almost buy another printer!) or learn what is involved in refilling.
Even though you rarely printed anything but black, the colors are used up over a long period of time, just to keep the nozzles open. The printer periodically "prints" to a place where the unused ink goes.
Zeldar - I can see that you are a newcomer to this forum and/or any usergroups regarding inkjet printers. Periodically these printers do an automatic cleaning routine that pulls ink through the nozzles. This is done to keep the nozzles free from ink drying up in them. When you print black text many of these printers also use some color ink in making up the black color you see on the paper. If you let the ink cartridges run dry two things will happen. You will get the ink that is in the nozzles drying up, and when the printer tries to print using the empty cartridges you will damage the nozzles for that particular empty cartridge. Canon printheads use small heating elements in the printhead nozzle area to create the "bubble" that propels ink onto the paper. The ink also acts as a coolant so that the heating elements don't burn out.
This technology works extremely well as long as you print fairly frequently and use all the colors. You also have to be observant of the ink levels and replace cartridges when they show empty on the monitor. I am not making an excuse for the Canon company, but they don't "blithely use up the inks"; They are used to keep the printhead functioning in addition to being used for their obvious printing function. This is true of all the inkjet printers from every manufacturer.
Actually the Epson printers use pressure to squeeze the ink on to the paper I quote.
MicroPiezo print heads are at the heart of every Epson ink jet printers. These print heads are able to achieve high quality results through microscopic nozzles, or holes on the print head, from which the ink is fired. Each of these nozzles has tiny, piezo electric elements, which vibrate tens of thousands of times per second, allowing the nozzle to fire ink droplets onto the page at extremely rapid rates. No heat is involved in the printing. This ensures greater accuracy when firing ink droplets precisely onto the page. And, it gives the printer greater control over ink droplet size. MicroPiezo technology ensures uniform, stable ink droplets with no satellites or misting.
They can block and clog if let run dry and due to the small nozzles can be hard to unclog