Ok Bob, first off your Jeep has A computer, all vehicles that have fuel injection, if there is wires going to the injectors are computer controled. There are some years of jeeps that used a different type of oxigen sensers that don't operate like a normal O2 so an EFIE wont work.
you need to back off the liquid fuel that your fuel system is feeding your engine. All vehicles factory fuel systems are designed to run so rich it borders on flooding, ( I call this flat earth technology).
You need to cut back on the liquid fuel to make room for the HHO vapor by making the computer think it is hotter and under less load than it realy is. You can do this by putting resisters in series with your air temp senser,and coolant senser, also by puting a potentiometer (an adjustable resister) in series in your MAP senser return wire from the MAP to your computer.
There is information on how to do this the web if you look for it. Get a manual for your Jeep, Chilton manuals have very good info on how your fuel system and sensers work and have wiring diagrams on what wire is what on each senser.
I am being vague on purpose because you need to do your homework, if you just start to mess with your senser readings with out understanding what you are doing or why you could realy mess things up ang cost you big money in repairs or destroy things, posibly even burn up your engine. so do your homework and don't do this blindly.
If you do this corectly you will see your fuel gauge move slower.
Have fun. Dale T. in Minn.