Here is the Civic shop manual which is ten times better than the Haynes...
http://www.crxpower.net/~silverkorn/...hop_Manual.pdf
Go to fuel/emissions and blow up the pic. It's not a very good rendering. I'm sure there is probably a better pic somewhere. BTW, the 88-91 Civic and CRX are very similar that is why they're referred to in the same discussion. GL