why poor gas mileage?

[cjdook]

394000

i have an 85 cj7 with the 258. I have the carter carb and am only getting less than 12 mpg. This seems ridiculous. What could be the problem. Im thinking it is the carter carb. I bought a weber 32/36 and putting it in on monday and also am installing the juicebox ignition upgrade. Do you guys think that the carb is the problem and that installing a new one will increase the gas mileage.
What kind of gas mileage do you guys get on your cj? Thanks.
aaron

 

[JRUK]

395000

Cjdook,

Well, welcome to the world of Jeeps. I've got the Weber and the TR upgrade and only get 13 mpg, so don't keep your hopes up...

Rene

 

[JRUK]

396000

Cjdook,

Well, welcome to the world of Jeeps. I've got the Weber and the TR upgrade and only get 13 mpg, so don't keep your hopes up...

Rene

 

[Jeeplover]

397000

Originally posted by cjdook:
i have an 85 cj7 with the 258. I have the carter carb and am only getting less than 12 mpg. This seems ridiculous.

I have the same setup on my '81 and get about the same mileage. I had been thinking the same thing as I have seen info indicating the mpg should be closer to 17mpg. I think part of the problem is the age of the technology we are talking about. Remember these ar 15-20 year old engines and technology we are discussing. Jacobs makes some interesting claims in their ads. Anyone with proof to suport their claims or refute them? I am running 31's on my CJ too. I finally got around to putting a tach on about a week ago. Surprise... at 65 mph in 4th gear I was turning about 1800rpm. I believe part of my problem is my gearing at the differential. These numbers are a bit below the optimal engine speed for good fuel efficiency. I looked on the gearing chart on this site and was off the bottom end to be able to determine gearing! Just some theories and thinking out loud. Any input (all is appreciated)?

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If you didn't break it you didn't play hard enough; A bad day Jeepin is far better than the best day at work.

 

[stilllearning6]

398000

My mileage is approx 10 mpg. I have an 88 with 4.2 BBD , 120,000 miles , oil in air box . That's after rebuilding carb , replacing all vac hoses, air filter , plugs ,fuel filter , CTO switch . I am halfway into TR upgrade-still fashioning an ign coil mounting bracket. Hope the TR will have an effect. It seems to get applause from the forums.

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[sillsmack]

399000

Geez...you guys make me feel pretty good about me old '77 304V8.

I have been lamenting for years about my 11mpg on highway. I once checked it offroad in low range = 4.5mpg....but that's to be expected.

I'm surprised. I would think you're 6's would get more out of a gallon of fuel than you guy's do.

I've been looking longingly at some great deals on used TJ SE's which come with the 4banger.

But the 4 needed more poop for me. I thought about 5.88 gears, but then it would self destruct on the freeway.

I guess I could locate a rolled chikaree and stuff the 4.0L into it, but, who has the time ?