Why does it crank and crank and crank but will not start?

I did the deal where you turn the key 3 times for codes and the only one I get is 12.before I got the new ECU I had 2 other codes but I can't remember what they were.

yes,that code is for the battery being disconnected,it will clear it's self.you need to check for spark,also fuel pressure test.

I had a friend of mine check for spark about a month ago and said it was getting spark, and as far as fuel pressure I don't know how to do that and like I mentioned, I ain't no mechanic. I only know basic stuff like oil change filter, air filter , stuff like that.

need to get that friend to check for spark again!also,you can rent the fuel pressure tester at Autozone to test your pressure.part number is 27167.it's $150.00 to rent it.you get all your money back when you return it.