Its a funny thing with Toyota. In Australia the '01 echo is rated to tow 1500 lbs. In Europe its rated to tow 2000 lbs. In Canada and the US, it has no towing rating and they don't recommend you tow with it despite the fact that it comes pre-drilled from the factory for a tow hitch should you want to install one.
I think the difference from country to country is related to legal liability. Personally I have been towing with a 2000 echo for 3 years, up to 1500 lbs. I've experienced no damage or problems whatsoever. I do drive carefully, turn overdrive off, go slow, leave plenty of room between me and anything in front of me, etc. My echo has 170,000 miles on it and is still going strong.
-I'm in Australia and have a 2003 1.4 Toyota ECHO hatch and it can tow a horse trailer!!!! a light horse trailer with only one pony/horse in it, but still! so i think that must be about 750kg for horse trailer & 550kg for a horse = 1300kg!! and its still going ok
3.5 Liters
If you are asking if you can tow with a Toyota echo, the answer is yes. See related link for a video of a Toyota Echo towing a small trailer (and off roading).
yes
In the gas tank. I have 2001 Echo.
2001 Toyota Echo doesn't have a timing belt.
http://www.carspace.com/guides/Toyota-Echo-How-to-change-oil
http://pdftown.com/2000-2002-Toyota-Echo-Service-Manual.html
For my 2002 Echo it is 3.7 Liters with a filter change.
3.6 litres
3.6 liters
timing chain.
see link