mideerslayer

I picked up this 97 jeep a months ago and was only putting in like $20 at a time, well I sea-foamed it, replaced the plugs, wires,cap, rotor and filled the tank

Right now i have put 157 miles on it and i have a 1/4 tank left.

The plugs that were in it were gapped at .085 where the spec sheet said to have them gapped at .035.

Also it is hard starting now it takes a few cranks and then turns over, but when i am driving it runs like a raped ape.

I do have a 2" lift and 31's, but i didnt thing that i would get this bad of gas mileage.

No ck engine lights are on.

Also brand new air filter and cleaned the throttle body.

What should i look for? I am not looking to get 30mpg but this seems bad

jronald

You have not told us what your mileage is yet. With Jeeps its OK, Bad and God awful. Based on your set up, you should be getting Bad.

Ron

mideerslayer

It has 225,000 miles it is auto 4 dr, like I said other then a hard satart,it runs great except the fact that I have got only 150 miles on 3/4 of a tank

The Blacksmith

you need to calculate the size of your tank. vs how many gallons it takes to fill it up vs how many miles driven, and this will give you a rough idea of mpg, but its by no means scientific.

say you drove 150 miles on 15 gallons = 10 mpg but there are so many varibles, that its almost impossible to get an accurate number.

DualSportDad

welcome to the club man. i have a 97 auto with a 3" lift, 31's and a surco rack that gets 11-13 and i have gutless 98 that is stock with 5 speed that gets an average of 18-19. i never guess a 3" lift and some tires would make that much of a difference, but i guess it does.

413maxwedge

The higher the lift the more air resistance ,bad for gas mileage, more tire less gas mileage etc,etc.

gvns8

I am going to go against the grain and say that I think it is easily possible to get 16-18 mpg on xj's regardless of the size of the tire etc, as long as you have the the right gearing on your axles, correct speedo gear and accurate speedometer. If the aforementioned items are all setup properly on your xj, then I think you have something wrong with your jeep if you are not getting at least 15mpg.

There are many possible causes to poor mpg's which most likely have something to do with the ignition system (spark plugs, coil, crank/cam sensors), fuel system (fuel pump/regulator, leaking fuel line, evap leak, injector leak), or poor engine compression (multiple causes such as blown head gasket, cracked head, etc.).

I know we can't expect xj's to run like they are straight off the assembly line, but if everything is functioning properly your mpg should not be 10mpg. But like others have mentioned you may not be calculating your gas milage right or have an inaccurate speedometer.

The best way to find your mpg's is to fill your tank all the way up (keep pulliing the trigger until you can't fit any more gas in there from the gas pump) then reset your trip gauge and then next time you refill your tank fill it all the way once again and divide the trip miles by the gallons pumped out.

DualSportDad

i would never suggest anyone keep pumping gas into the tank till it won't take anymore. you're just asking for a spill and for damage to fuel system evap parts.

i go to the same gas pump at costco and fill up everytime till it clicks off. i do the math and i have the correct speedo gear. i have new injectors, spark plugs, cap, rotor, wires... all the goodies. my gas mileage still blows.

NPx

Did you install the 31" tires? My guess is the oversized tires are throwing off the speedometer & trip meter. You are actually going further and faster than you think.

In every situation I know of when the speedometer is corrected for the change in tire size the mpg is almost the same as with stock tires. My 98 XJ is on 33s but the speedometer has been corrected and runs almost exactly true to distance. If it goes 100 miles based on mile markers on the interstate the odometer reads almost identical.
hth,
DougN

DFlintstone

I agree. I'd check that odometer first since it's new and on 31's. I try to park at the same pump (leveled the same), and go three clicks at "full throttle". Don't think I'd want to top it enough to find out what that does with the evap. system.

DualSportDad

on my 97 (the lifted one with 31's) i changed the speedo gear to the correct one. i checked the speedo accuracy with gps on my phone. my speedo reads about 2 mph faster at 50 mph than what i'm doing. so at 50mph on the speedo my gps shows 48 mph. the same happens on my bone stock 98 xj. my 98 with 215,000 miles gets about 19mpg and my 97 with 170,000 miles gets about 13 mpg.

firdale

Just bought a surplus cherokee from our state's dept of Ag. Every time you look at gas gauge seemed like it was going down. Figured gas milage must be awful, but first tank was 20.545. Second was 20.851. (Same gas station, same pump, filled until it wouldn't take any more). Comute on a gravel road (actual rally america race stage) daily so have concentrated on keeping it going fast enough to stay in OD. Gets kind of exciting some places, but seems to be working for milage. Am going to try a different station that claims no alcohol in their gas, and narrower tires in a few weeks when replace them. Then perhaps injectors and airbox change. Got cherokee to get better milage than thirsty pickup and so far it is, but hope it can be better yet.

Mendax13

well sea-ing as you seafoamed it. maybe you should check your 02 sensors and make sure they're good and clean. ive heard they can become dirty after seafoam. just a thought.

413maxwedge

This is for the guy's that keep filling the gas tank after the kick off point, don't come back later in your jeep's life when you start getting Cel's for the emission's.lol