Gas mileage lower to 8 mpg

it is fuel injected and the injectors are in a manifold at the inlet manifold
most misfires are injector related ( dirty tips , low fuel pressure or injector wiring harness) get a workshop manual from an auto parts shop

on normal that trk should be around 6-7 gallons used per one hundred miles drove. i based that at 15 mpg. now that is also based on a V8 engine. now 1 gallon of gas is 3.78541178 liters which totals 12 galons of gas to 45.42494136 liters. This would mean that it took 12 gallons of gas to travel 100 miles which totals 8.3333333333 mpg. not as good as i would have thought. 8 miles per gallon (mpg) hell that engine must be a big block 460. If it is that big cubic inch i could understand but any other motor should do better mpg than 8.3. so i agree that is not normal, tune up, or look for fuel leak in the fuel supply or( feed ) line. From the tank to the motor. This must be a canadian truck yes? well hope for the best or trade that guzzler in for a new breed. stay warm!

can you smell raw fuel when the vehicle is running? smell the exhaust when its idling.. if it smell like fuel really strong, you need to replace o2 sensor.. the o2 sensor is what tells the vehicle the air/fuel mixture, thus if one is bad it will either run rich (uses too much fuel) or lean (dont get enough fuel) hope this helps.. also check out the fuel press. regulator if your vehicle is equiped with one.. the o2 sensors will usually kick the check engine light on.

you can get pressure specs from your local parts dept, and check injector signal with a noid light

Next time when cold and it will not start remove a spark plug or two and see if the engines flooded. If so there are two things that come to mind; 1, worn injectors, leaking as engine sits with time causing difficult starts 2: bad oxygen sensor, if failed engines tend to run rich and the ECU may have your injectors pump heavy amounts of fuel to keep from running lean; often times you'll see poor fuel MPG if O2 sensor failed.

I hope this may have assisted you,
Tom

Per my Chilton's manual tehe bolts should be (cold engine) 65 to 72 FT. Pnds., the cam shaft bearing bolts should be 8x25 = 15 - 19 Ft pnds and the 8x65 should be 14 - 15 Ft Pnds.

The sequence is as follows for the (10 ) head bolts:

7 - 5 - 2 - 4 - 10

9 - 3 - 1 - 6 - 8

I hope this may help,
Tom

Dimensions Exterior Length: 146.1 in. Width: 62.4 in. Height: 53.1 in. Wheel Base: 89.2 in. Curb Weight: 1870 lbs. Interior Front Head Room: 37.8 in. Front Shoulder Room: 51.6 in. Rear Head Room: 36.5 in. Rear Shoulder Room: 50.5 in. Front Leg Room: 42.5 in. Rear Leg Room: 29.8 in. Luggage Capacity: 10.4 cu. ft. Maximum Seating: 4 Performance Data Performance Base Number of Cylinders: 4 Base Engine Size: 1.3 liters Base Engine Type: Inline 4 Horsepower: 100 hp Max Horsepower: 6500 rpm Torque: 83 ft-lbs. Max Torque: 5000 rpm Drive Type: FWD Fuel Data Fuel Fuel Tank Capacity: 10.6 gal. EPA Mileage Estimates: (City/Highway/Combined) Manual: 24 mpg / 32 mpg / 27 mpg
Range in Miles: Manual: 254.4 mi. / 339.2 mi. / 286.2 mi.

check you fuel line to make sure vehicle is getting rite fuel pressure and if you are getting the rite pressure check you distrubitor wiring make sure they are in the right firing order

start with simple thing like a tune up change fuel filter, air filter and plugs pvc valve ect. but if you can't afford just change your fuel filter. hope this help buddy

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