I have a 93 Cherokee with a 4.0 I am getting 80 to a 100 miles a tank. I have replaced 02 sensor map sensor and both temp sensors plus the thermostat. Any suggestions?

 

sounds like your running really ritch..o2 would be to blame....maybe try some sea foam...
When is the last time you tuned her up and did an oil change...also pull out the dip stick and if it smells like gas.. You have bad seals on your cylinders. Most likely.

 

I would say start with a full tune up. Plugs, wires, cap, button, run some injector cleaner(or get new, better injectors) air filter. What o2 sensor did you replace?

 

Does it run poorly? Do you often leave it running w/o going anywhere.. for hours at a time? 5mpg is really bad mileage. Any chance someone is stealing your gas?

 

Do you have a small gas tank?? Sorry I just wanted to be a smart a$$ this morning.. Good luck.. sounds like everyone has sound advise..

 

This is what I would suspect. My step daughter complained about crappy gas mileage in her Exploder, I put a locking gas cap on it and her mileage increased per tank.

 

This. Which one did you change? The upstream one is the one that you need to change. Downstream is just for emissions. Has no effect on MPG what so ever.

And / or this.

 

could be faulty O2 sensor you replaced. Put the old one back in and see if anything changes.

 

just curious have you been burning oil? or have you ever had a head gasket blown or valve cover gasket gone bad on it? intake/exhaust manifold gasket? check your filter for oil too.

I ask because if a gasket goes bad sometimes oil will seep out an into your intake and flood your filter. clog your intake system up and then your just sucking up muck/sludgy crap. especially if you keep driving it. im not really sure how to explain it better then that.

I had this happen to an xj i picked up for $800 that sat for 4yrs. i was wondering why i had crappy fuel milage and it turns out it was the intake/exhaust was just pumping out brownish/blackish oil crap. After I replacing the gaskets and cleaning the intake system with the new exhaust/intake manifold gasket it ran just fine milage wise.

 

My jeep only has 1 02 sensor air filters clean and no gas smell on dipstick. Pretty sure my gas isn't being stolen. Gonna change head gasket and see what happens not sure what else to do.

 

...is it even possible to get that poor of mileage? I'd imagine running that rich would stall the engine, or at least make it damn near impossible to drive.

 

Where is that o2 sensor at?

 

Why change a head gasket if it is not the problem?

 

Smell your oil. if its loaded with petrol then you will know it. Once you establish that then work your way up. Im running stock gears on 35's and dont get that bad of milage

 

Who the hell steals gas? LOL

I thought there was a screen or something in the fuel filler now so you can't get a hose down there. I guess it would depend on the year though.