Civic EG

ok so for some reason my car only takes 7 gallons to fill up from being empty.
i know that shouldn't be right?
any idea why?
its a 1992 civic cx

that happend on my buddies em1 but that was because the dumbass that owned it before him jacked it up on the gas tank lol

so it can be that the fuel tank it probably bent
i bought it at an auction but when i checked underneath it everything looked fine, nothing was bent at all

does it take 7 even or 7 and some change because my 92 hatch used to do that and i always thought it was a 8 gal tank but idk if they even came with an 8 gal tank... but my 93 is 10 gal for sure

it takes like 7.5gal. it has never reached 8gal
i been doing some reasearrch and they are like 11.9gal
so i should be at least at the 9-10gal

eg's have this prob where our gas guages tell us the wrong reading..

when i hit empty i fill up on like 8 gallons too
and my sedan tank is a 11.9

so the way u can do this is get a gas can and fill it up
fill ur tank till it cant hold anymore.. then reset ur odometer
and when u run out of gas check how many miles u went and divied that by the size(gallons) ur tank is that is ur mpg.. so after that just fill up according to your miles not gauge

i get like 36ish mpg..
so thats like 428.4

so i just fill up every 400 miles

i have done that i have let my car stall while driving it and filled up and still took less than 8gal. i get around 200miles
per tank though so i always know when to fill up. only suxs when i take long trips i have to stop for gas more frequent than my brother's integra