1. #1
    Join Date
    Nov 2002
    cleveland, ohigho


    90 yj 2.5L 5 speed

    i just took a 200 mile trip today and found out that i am getting horrible highway gas mileage. with a 14 gallon tank all i got was about 210 miles...15 MPG ON THE HIGHWAY?

    my tires are inflated properly, i just had a new, remanufactured engine put in a couple of months ago, new plugs, wires, air filter, etc., new cat and muffler.

    wasn't driving fast either, just 60-70 mph without any major accelerating.

    any other ideas on why its so bad?

    maybe a sensor? wheel bearings? anything?

    i guess for some people 15 mpg is normal, it is just that i know i used to get 17-19 mpg

    a couple years ago.[addsig]

  2. #2


    That doesn't sound too bad. You got to remember that you are trying to push a barn door at hwy speeds. Jeeps are not very areodynamic. Or the motor isn't broken in yet. It takes awhile for everything to seat properly.[addsig]

  3. #3


    keep in mind the gasoline is "winterized" is some states. This causes a lot of folks to drop 2-3mpg during

    the winter months. I wonder if a drop in efficiency was taken in to account when they started that crap.

    Is it truely environmentally friendly if everyone then uses more gas?

    On a slightly related topic. You might be able to turn your 14gal tank in to a ~19-20gal tank for nothing.

    Run a search on google.com "YJ gas tank increase" or mod, or fuel or whatever. I don't have the link

    handy. I know on my TJ, I didn't mind the mpg near as much once I started getting 20gal per fillup. The mod

    is a little more work for TJ's. YJs have it easy for this one.

    Also, are the tires stock size? If not were things adjusted in the odometer/tripometer to take that in to

    account? If you're not sure what size the speedo was set to, get on a highway, go 60mph (important), and

    time yourself for one mile (markers on the side of the road). It should take exactly sixty seconds. If not,

    do some math to figure out if your 5%, 10% or whatever off. Use this when adjusting what your trip says,

    then do the mpg calculation.


  4. #4
    Join Date
    Dec 2002
    Boca Raton, FL


    I agree with bigTlilODD, that sounds about right to me. I had an 89 and got about that on the highway. Not much you can do about that. I ended up buying a 99 Grand Cherokee with the V8 last month. Talk about bad gas mileage. 13.5 city and 16-17 highway. I had a 00 TJ 5spd 4 banger and I got about 19 on the highway. Nature of the beast I guess.[addsig]

  5. 1049636

    Jcooper what do you mean when you say winterized ,I live in Texas and I would like to know if they do that here.[addsig]
    78\'CJ5 Red, TFI conversion.

  6. #6


    <TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font class="pn-sub">Quote:</font><HR></TD></TR><TR><TD><FONT class="pn-sub"><BLOCKQUOTE>Jcooper what do you mean when you say winterized ,I live in Texas and I would like to know if they do that here.</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR></TD></TR></TABLE>

    If it's done in your state, look at the gas pump and you should see "%$#% added from SEP to MAR to give

    you cleaner air." Or some other touchy feely thing. States like Cali add crap year round. When I left Cali my

    mpg went up from 16 to 19-20 (97 TJ 2.5) right after the second fill up in Nevada... I don't remember if

    I saw it when I was in Texas, tho.


  7. 1049849

    To make you feel a little bit better.. My cj7 with a chevy 350 motor and 35" tires gets about 11 mpg on the highway going downhill!!![addsig]

  8. #8


    I just put a new jasper engine in my 88 YJ 6cyl. My gas mileage was horrible but after about 1000 miles on it it got much better it just needs to be broken in. [addsig]

  9. 1049859

    If you were to look at a spec sheet printout on a Jeep one would think that a Jeep would fairly good gas mileage. Weighing around 24-2600 lbs. with a 2.5 4 banger or 4.0 inline 6. These numbers kinda resemble an import car that gets 35 mpg. But thanks to our wonderful aerodynamic design, you might as well pull a parachute behind you. But 14 mpg isn't that bad really, just do the 20 gallon tank mod and it won't seem as bad....maybe

    Our wonderful design is what makes us so easily recognizable!!!!![addsig]

  10. 1049874

    Ive got a 10 bolt rear end with 2.73 gears that will really

    improve your gas mileage![addsig]

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