The ECM will store whatever code it is setting. Simply go to:
http://www.chevythunder.com/fuel%20i...g%20pg%20a.htm
And you'll find everything you need to know about how to check the codes, what the codes are, and what possible issues they may point to. Keep in mind that this is a TPI site, so if something doesn't make sense, or apply to your TBI, give me a PM, and I'll try my best to help you out (the codes all mean the same thing between TBI / TPI btw)