1986 honda civic, HORRIBLE gas mileage and why?

[BringExtraDragons]

Hello all, a newbie to this foruma and I'm one of those people who have no clue about anything on a car, parts, how to fix, its all a mystery. Anyway i bought a cheap 1986 honda civic and it's a quiet little car, runs good. One thing i've noticed is the horrible horrible gas mileage so far, i can't quite understand it. The car is really light weight and small, but its sucking gas like a battle tank. I haven't calculated the exact mileage yet, not fully sure how to see how many miles to the galon it gets...but i did fill it up once and i set the mile gage thing to zero. By the time my damn gas tank was empty...it only chewed up about 120 miles...so a whole tank a gas after driving a little over 100 miles? something seem terribly wrong with that?

[crazi-85crx]

they've got small tanks, but that still sound pretty low. sound like time for some basic stuff like an oil change, new filters, and sparkplugs.

[lxndr]

Which model? DX or HF? Civic or Civic/CRX? The HF CRX has the smallest gas tank of all models so if there's a problem with fuel efficiency, it will drain pretty quickly.

I'd start by giving it a tune up, and checking for vacuum and fuel leaks.

[jwaj2002]

fill it up 3 times, write down mileage and the amount of gas each time, then add the mileage, then add the amount of gas, then divide mileage

if you have an 8 gallon tank and your getting 120 miles on that 8 gallons then your mileage would be 15 miles to a gallon, my old honda got 300 miles on 8 gallons of gas during the summer, and around 340 during the winter