My 93 just when from getting 20mpg one week to 9.8mpg the next. no noticeable difference in drivabiltiy. I do not see any gas leaks, pulled the vac. line off of the regulator to see if its leaking(its not), not smoking out the tailpipe. I can't find anything

 

Maybe someone stealing your gas.

 

I can actually watch the gauge. I am using a quarter tank to work and back.

 

O2 sensor. that was my gas mpg problem on my 90xj. mine has a emissions timer under the dash that goes off every 30,000 or something to tell you the O2 needs to be changed but many people unplug them do to the fact that you have to buy a new timer cant rest it.

 

Check for fuel leaks if you are using that much.

 

*When was your last tuneup? The correlation of tuneup hardware to gas mileage cannot be overstated. Fresh Champion copper plugs, quality plug wires, distributor cap, rotor and fuel filter. Money well spent. Check your air filter while you're at it....

*Oxygen sensors get "lazy" over time, usually long before they set a code. For a 93, I recommend using NTK as that is the brand of O2 sensor your XJ came with off the factory line. Oxygen sensors have a finite lifespan of between 100k-150k depending on engine efficiency and condition.

 

What mpg where you getting before and after?

 

I was getting 200mi to a tank before O2 sensor replacement after i got about 250 out of a tank. I have a 2in lift and 31in M/t, front bumper with winch and 355,000mi so i get bad mpg any how

 

I check my fuel pressure and exhaust back pressure both are good i will check the o2 readings tomorrow

 

Could be bad gas did you use a different brand?

 

I rebuilt this engine about 40k miles ago. It got all new ignition parts and an o2 (denso) then. I checked for a gas leak first. Lines are dry from tank to injectors

 

Tps is bad. It reads 100% just off idle, then normal, then when you get to 69% it jumps back to 100% and stays. It started bogging real bad at stop signs yesterday. It died probably 10times on my to work then when i got there the radiator was leaking. So today is jeep repair day.