Zebvance Posted February 22, 2012 Share Posted February 22, 2012 I have a 1988 keep Comanche. Just got it about a week or two a go. It has stock gears and a auto tranny 4wd. It has a 4.5 inch lift and 31/11.50/15's. From filling up I'm guessing has about a 14 or so gallon tank. When I went to fill up again I looked at my trip and how much has I had used. I had used 13.1 gallons and got 144 miles to the 13.1 gallons. That sucks. It was all city driving also. The engine has 103,000 miles. Is this gas mileage normal for this set up on stock gears? On highway it really dosent have much more in it at 70 mph. Could I expect better or worst mpg on highway? Link to comment Share on other sites More sharing options...
bbe Posted February 22, 2012 Share Posted February 22, 2012 My stock 88 will get about 18 if I'm not too lead footed. bbe Link to comment Share on other sites More sharing options...
Pete M Posted February 22, 2012 Share Posted February 22, 2012 16 and 23.5 gal tanks are found under longbeds 18 gal for shortbeds Link to comment Share on other sites More sharing options...
AMCJeepMJ Posted February 22, 2012 Share Posted February 22, 2012 I keep track of my fuel mileage on Fuelly. Link to comment Share on other sites More sharing options...
cody4359 Posted February 22, 2012 Share Posted February 22, 2012 did you change your speedo gear when you bumped up the tire size? i alwas get worse mpg in the winter due to the crap the put in the fuel. ive been averaging 12-13 on 33"s, an you will get better mpg on the hyw/fwy, just don't expect great mpg goin 70 compared to 55-60 Link to comment Share on other sites More sharing options...
Zebvance Posted February 22, 2012 Author Share Posted February 22, 2012 16 and 23.5 gal tanks are found under longbeds18 gal for shortbeds Yea that's what I read too. Idk why but mine has a 14 gallon tank. There is no way I can get more that 14 gallons out of it. Link to comment Share on other sites More sharing options...
Zebvance Posted February 22, 2012 Author Share Posted February 22, 2012 did you change your speedo gear when you bumped up the tire size? i alwas get worse mpg in the winter due to the crap the put in the fuel. ive been averaging 12-13 on 33"s, an you will get better mpg on the hyw/fwy, just don't expect great mpg goin 70 compared to 55-60 No I didn't, the speedo is acually all in kilometers. I got 220ish k to the tank which comes out to like 140 miles Link to comment Share on other sites More sharing options...
Pete M Posted February 22, 2012 Share Posted February 22, 2012 16 and 23.5 gal tanks are found under longbeds18 gal for shortbeds Yea that's what I read too. Idk why but mine has a 14 gallon tank. There is no way I can get more that 14 gallons out of it. Â hmmmm, maybe the fuel gauge isn't reading properly or the float is stuck and you're not actually at empty when it says. :dunno: Link to comment Share on other sites More sharing options...
Zebvance Posted February 22, 2012 Author Share Posted February 22, 2012 Going to take some Measurements next time I have a chance Link to comment Share on other sites More sharing options...
Blue88Comanche Posted February 22, 2012 Share Posted February 22, 2012 16 and 23.5 gal tanks are found under longbeds18 gal for shortbeds Yea that's what I read too. Idk why but mine has a 14 gallon tank. There is no way I can get more that 14 gallons out of it. Â hmmmm, maybe the fuel gauge isn't reading properly or the float is stuck and you're not actually at empty when it says. :dunno: Â the tank on my 88 MJ does the same thing, only 14 gallons till empty.. but the gauge moves from full to empty throughout the use of one tank of gas. Link to comment Share on other sites More sharing options...
Pete M Posted February 22, 2012 Share Posted February 22, 2012 ever run it dry? Link to comment Share on other sites More sharing options...
jimoshel Posted February 22, 2012 Share Posted February 22, 2012 Depending on float (filter) level, there will be 1-2 gals of unusable fuel remaining in the bottom of the tank. Link to comment Share on other sites More sharing options...
Zebvance Posted February 22, 2012 Author Share Posted February 22, 2012 16 and 23.5 gal tanks are found under longbeds18 gal for shortbeds Yea that's what I read too. Idk why but mine has a 14 gallon tank. There is no way I can get more that 14 gallons out of it. Â hmmmm, maybe the fuel gauge isn't reading properly or the float is stuck and you're not actually at empty when it says. :dunno: Â the tank on my 88 MJ does the same thing, only 14 gallons till empty.. but the gauge moves from full to empty throughout the use of one tank of gas. Â Â That is exactly what mine does Link to comment Share on other sites More sharing options...
Blue88Comanche Posted February 22, 2012 Share Posted February 22, 2012 ever run it dry? Â i have not, but i did find out the low fuel light works Link to comment Share on other sites More sharing options...
xjrev10 Posted February 22, 2012 Share Posted February 22, 2012 To me, 10 mpg sounds about right for strictly city driving. At least thats my expirence with a AW4 L6 XJ. Â I get right around 20mpg hwy with my 88 4.0/Pukey Link to comment Share on other sites More sharing options...
cruiser54 Posted February 23, 2012 Share Posted February 23, 2012 FYI, it's never been established that your speed is accurate with the oversized tires. Ever check it with a GPS or mileposts? That could be the whole issue...... Link to comment Share on other sites More sharing options...
mvusse Posted February 23, 2012 Share Posted February 23, 2012 FYI, it's never been established that your speed is accurate with the oversized tires. Ever check it with a GPS or mileposts? That could be the whole issue...... Â And even if your odometer does read correctly, depending on driving habits, 10mpg around town on wide 31" tires is not impossible, especially if they are an MT tire. On stock tires (27" and a lot narrower), highway driving at 60mph should be able to get 24mpg. Â As far as your tank size goes, the low fuel light goes by the same signal as your fuel gauge. To find out what size your tank is you would have to drive around with a can of gas in the back and run the tank completely dry. Don't forget to fill the can again when you get gas after that to make up for the gas your poured in to get to a gas station. Fuel gauges are nice, but can not be trusted to be accurate. Even on a Chevy Cobalt that can show me fuel remaining in miles I drove more than 50 miles after it said 0 miles remaining... Link to comment Share on other sites More sharing options...
Backroads Posted February 23, 2012 Share Posted February 23, 2012 I was getting 19-20 with stock 88 2WD, now with 4wd and 33's I'm about 12 max. 5speed. Â I did put in a new gas tank at one point and when filling it from a new bone dry tank, it took a good 2+ gallons before it even registered on my gauge that there was any fuel in the tank. Good to know when my needle is buried at dead E, theres possibly still 2 gallons in there yet! :chillin: Link to comment Share on other sites More sharing options...
Blue88Comanche Posted February 23, 2012 Share Posted February 23, 2012 my uncle said that most gas tank/gauge setup will have 1 to 5 gallons of fuel as reserve, this way when and if you hit empty you still have the ability to get to a gas station. his old Camaro on the other hand, once it hit E you were out of gas. Â so if we have a 18 gallon tank and it says we are empty and it takes 14 gallons to fill up, then we should have a 4 gallon reserve... according to my uncle.. Link to comment Share on other sites More sharing options...
drcomanche Posted February 25, 2012 Share Posted February 25, 2012 This sounds about right to me. I used to fill it up as soon as it hit empty and I would get anywhere from 12 to 14 gallons into it. Since i had installed my gas tank, I knew it was an 18 gallon tank, and I decided to run it after empty. Mine has no problem running a couple more days on the gas in the tank. But then again, I have no problem going 2 weeks without refueling, so I'm getting into the high teens if not more on gas mileage. Pretty good with all the parts on it considered. Link to comment Share on other sites More sharing options...
Comanche County Posted February 25, 2012 Share Posted February 25, 2012 If you are relying on your odometer, it will be off with your tire size. Yes, the 31s will hurt your gas mileage, but I think its mainly the gears not matching the speedo. Its not that bad considering you said it was all city driving. Â Confirm it again with a GPS to measure actual distance driven divided by fuel, start with a full tank, drive, fill up again, do the calculation and see if its any different. Link to comment Share on other sites More sharing options...
cruiser54 Posted February 25, 2012 Share Posted February 25, 2012 My point exactly. Link to comment Share on other sites More sharing options...
jpnjim Posted February 25, 2012 Share Posted February 25, 2012 I generally get 12-15 mpg out of my 89 (stock 4.0l auto 40k mi 30" tires), this last tank I got 10.5mpg :( All city driving. The most I think I ever squeezed into the tank was 16 gallons. That's $60+ now. Link to comment Share on other sites More sharing options...
Truckcom Posted February 25, 2012 Share Posted February 25, 2012 For the record, my 88, 4L, 4x4, pewjoe, gets about 22 Hwy and 20 +- around town. I determine this by gallons used at each fillup. My odometer reads 3% under, I assume, due to the 235/15 tires rather than the original 225's. If we didn't have the ethanol, I think it would be much better. I should note too that I drive like a hypermiler. Link to comment Share on other sites More sharing options...
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