Poor gas mileage on my jeep liberty

Check the fuel hose and clamps from the filler to the tank .check hose for cracks . The smell will probably be strongest in the boot.

Yes...the cap needs to be on there or the purge system will register a leak. The light may not go out right away but usually will after about thirty miles of driving. (computer needs to go through a complete self test cycle).

Well first, is the overdrive on or are you in the overdrive gear, also sorry to tell you but these v-8 jeeps get real bad gas mileage, i think highway mileage is 18 and city 14,if you were getting better mileage and the trany is actting up then that will cause the lower mileage, good day.

Drop in to autoparts place & get free code scan & go from there. (write it down & get back to us, or ask them at store.) Autozone & Pep boys I believe will do free scan.

could be either a bad thermostat or a plugged fuel filter try them first

Did this happen overnight or was it a gradual loss? Did you do any kind of repair before you lost the gas mialage? Is there a check engine light on or did it come on and go off? Did anything weird happen before the jeep got bad gas mileage? It's hard to diagnose a problem like this without actually touching the car.
Any other info might help me steer you in the right direction.

when was the last time you put in fuel injector cleaner? I put in Lucas Oil Injector cleaner every other or every oil change.

There are alot of factors affecting your gas mileage. Tire wear, tire pressure, wheel alignment, air filter, fuel filter, spark plugs, oxygen sensors, just to name a few. So to say what you need is just shooting in the dark without more information. I would probably start with your oxygen sensors, and then perform a tuneup. If your vehicle pulls to one side or the other when driving on the highway you need to stop into the shop for a wheel alignment.

to increase gas mileage make sure you keep on top of tire air pressure you can also have your tires filled with nitrogen instead of air also a K&N air filter does wonders and is good for lifetime worth every penny. another smart move is to use a fuel system cleaner regularly Lucas makes great products for this try local parts store.

well you may need to have it serviced even though your not too hard on it. try a complete tune up and see how the milage is affected

My Answer:

Poor gas mileage can be a result of many many things.

First of all you need to find out what is the factory normal gas mileage for your model year Jeep SUV. It should have said on your window sticker if you bought it brand new. If you are a 2nd or 3rd owner then a Jeep dealer would have info. Google search will tell you as well, and only takes a couple minutes to find.

I did a quick Google search and for a 2003 Jeep Grand Cherokee with a (4.7L V8 engine) the average mileage is roughly 14 mpg.

Not sure what engine you have as to options, etc?

How you drive will greatly change that number up or down depending on a number of driving and driver variables.

A few being -

Driving habits?

Tire pressures?

Engine tuned up?

Lube & oil/filter changes (every 5,000-7,500 miles? Air filter changes (every 10,000-15,000 miles)? Read your auto manual for exact recommended intervals.

How many people in the SUV on average?

Are you towing anything?

Type gas you are burning - BRAND? (See injectors below)

Area you are driving in (hills and valleys verses flat out,
etc)

Jeeps in general don't have a good track record for great mileage, and rough engine idling is always a clue that your fuel injectors are dirty. Typical on all Jeeps with port fuel injection systems! On Jeeps with dirty fuel injectors your mileage will go way down accordingly. If your not putting at least a 12 oz bottle of say Walmart brand Super Tech Fuel Injector Cleaner (~ $1 each) in your gas tank religiously every logged 1000 miles, or every 2 tank fill ups, then you are just inviting dirty fuel injectors and POOR fuel economy!

My 1993 Ford XPLR with a 4L V-6 engine (and ~ 160,000 flawless driven miles) gets roughly 22 miles per gallon on the highway with cruise control on, and about 17 around town on average. I religiously put a 12 oz bottle of the above injector cleaner in my gas tank every 1000 miles!! Of course I do all my own tune-ups, general repairs, and suspension maintenance (shocks, O2 sensors, trans oil changes, lube & oil/filter changes, code reading and clearing, etc) myself and it shows! I don't trust repair shops except for say Tires and Balancing at SEARS.

Hope that helps ease your mind about gas mileage as it relates to your Jeep there.

Frank