2004 Chevy Aveo cranks but won't start. Where should I start?

I believe that what you are saying is that it is turning over but will not crank...(run), not sure what your problem is, but I can help you to narrow it down. In order for your engine tp crank...start...run, you need three things to be right..#1 adequate compression, #2 ample spark, #3 the correct fuel/air mix. The first thing i would check is spark..reason, #1 failure of the 3. You can start by seeing if you have spark at the plug(S)...Just because you have it on one does not mean that you have it on all. 2nd most common failure would be no fuel...improper mix, you are fuel injected, so likely a sensor/computer issue...and the most uncommon of the 3 would be a compression issue. Which would likely not occur on all cylinders so the engine would still run, unless the cause was a broken timing belt. Gives you something to start on. Good Luck.Hope this helps.