so my 96 ZJ V8 is averaging 200 miles a tank, to miles per gallon approx. Just past a smog test with flying colors. Has 31" tires and 3 1/2" lift.
Jeep has 68500 original miles. What can I look for that could be causing this? Would a tune up help and if so what do I change? Any help and suggestions would be great. thanks

 

You're getting 2 miles per gallon and 200 miles to the tank, how did you fit a 100 gallon tank on a Grand Cherokee?

 

So...

The ZJ already gets horrible gas mileage (12-17 mpg stock):
http://www.fueleconomy.gov/feg/noframes/13206.shtml

And then you lifted it, added heavier tires, and other miscellaneous mods. I'm surprised that you're surprised that you're getting 10 mpg. It seems to fit the picture rather well.

A tune up is a temporary improvement for mpgs. As soon as the new parts break in, you'll be right back where you started. There's really no such thing as a lifted Jeep with stock mpg ratings. And there's very little you can do to increase your mpg ratings. Just ride that pedal like a feather or consider an alternative vehicle.

 

10, typo

 

understood, however it seems the norm is 12-14.... even for the lift 10 seems way too low. but it is what it is, thanks

 

Aftermarket intake systems, and exhausts can also affect your fuel economy. I find that getting something better than factory is few and far in between. Those engineers knew what they were doing.

 

Id suggest a bored throttle body. I just installed one for a customer, who is a nut for gas mileage, and he verified between 1 & 2 mpg improvement and better low end.

 

Regearing the diffs is the only sure way to regain the lost mpg.

 

Hey Busted! Why is it everybody that buys a Jeep loves it but doesn't like the mileage? Nobody ever gets good mileage with a "dedicated" 4 WD vehicle, and we know an all-wheel drive is not the same.

My Chevy K10 got about 8 mpg with 33X12.5's on it and it didn't matter if the front hubs were locked in or not. It had 4.11 gearing and TBI as well. Although, it WAS a tank!

 

My Powerwagon with a 440 only got 6mpg. I love getting 16.5 on average with the Jeep. I've been driving the wife's car since I hit a tweaker pedestrian last Thursday. The Jeep got a little dickered up, but I'm getting 32mpg in town in the Kia.

 

you cant say this then not elaborate on it

 

I love my zj, a true American gas chugger. i had the 4banger yj before this, still crap mpg. these are not commuter cars, so i bought my 2012 honda civic natural gas and i get 40 mpg and it costs a buck a gallon. Im really happy that half of my paycheck doesn't go to fuel because i drive 3500 miles a month

 

Try to replace the O2 sensors. They have a lifespan around 100.000 but i se that many change them at 70.000 so maybe its time to replace them?
You have a heated one(s) i think, so they should last longer, but they can fail and i replaced mine (i have one) and i got better MPG.

"Normally, the lifetime of an unheated sensor is about 30,000 to 50,000 miles (50,000 to 80,000 km). Heated sensor lifetime is typically 100,000 miles (160,000 km)."
http://en.wikipedia.org/wiki/Oxygen_sensor

 

My friend got a used corolla for commuting. He has a 2012 Tacoma dual cab 4x4. Just something you have to deal with one way or another

 

Your best option is to lighten your load!...I have a 91 Lerado and at first i was sold on having a 4x4, but the MPG started getting on my nerves to. But no matter what i have put into it only lightening the load improves the gas mileage...