There aren't any evaporative emissions codes for OBDI. That's not to say that it couldn't set exhaust codes, but I wouldn't bet all my money on that. To pull the codes, get a paperclip, jump the two top right pins on your ALDL connector (black plugin) located on the driver's side under the dash, turn the key to 'ON,' and then the SES light will start flashing. Count the flashes. It's gonna flash three Code 12s at you (one flash, a short pause, and two proximal flashes), and after that it'll show you the sequence of trouble codes. You just see how the flashes group to know what the codes are just like the Code 12 I mentioned. It'll store up to three codes, and it'll flash each trouble code three times. When the sequence is over, it'll flash you three 12s again. Also, you should really put a gas cap on it. You risk dirt getting in there and expediting the need for a new strainer sock, fuel filter, or both.