See that's just it. Everybody tells me "oh your fuel gauge is inaccurate." But that still wouldn't tell me why I can go from lugging it to the gas station to being full at aprox 11.5 gallons of gas. I just can't buy that there is another 4 gallons in the tank that I in theory could be using. NOBODY would drive a car that extra distance like that unless they were Kramer.

I can put more gasoline in my Sunbird, which has a 13.6 gallon tank.

 

http://cgi.ebay.com/ebaymotors/82-92...temZ8074477573

http://www.showcars-bodyparts.com/firebird82up.html

^^^ Both are 14 gallon

http://www.hawksthirdgenparts.com/inc/sdetail/32574
This shows at least 3 different fuel tanks for late 1980's F bodies.

http://classicindustries.com/pdf/f_fuel-exhaust.pdf (14 gallons on 82-92 F bodies)

14 makes more sense. 15.5 sounds too big. The strange thing is I don't remember the gas tank in my 88 IROC being any smaller than the LT1 and it did seem bigger than what is in my GTA.

 

I just went and checked the original owners hand book for my '88 and it says 15.9 us gal. (60.2 L) it's been years since I've allowed it to get that low and the most I can remember putting in it was 13 and some odd gallons. I do think the 15.9 include the filler neck also, and when they say 14 gal. they aren't allowing for this, and are just rounding off.

 

I know I've put at least 15 gal in the Iroc. When I got my 94 TA, it was OUT OF GAS. I put about a quart of gas in it and drove it across the street(about 50ft) to the gas station. I put 16 gal in it then.

 

My efi 305 88' gets about 12 mpg city , whch is mostly what i drive unfortunalty ...ive only been freeway with it twice where i got roughly 20... i normally fill it at like 1/8 tank...n from there i normally get 12 ish gallons