4.0cherokee

I have a 1999 Cherokee classic that had 119k on the Odometer. My fuel milage has been getting worse especially here lately. It just drinks the fuel. Like today just sitting there idiling for about 30-45 min it used up almost a 1/4 of a tank. When it is sitting there it has a vibe to it, a slight bounce would be a better description. When you go to the back end you can hear the exhaust kind or burp sometimes and then it will run ok then burb again. I really dont know any other way to explain it. Today I was able to get 10 mpg babying it. Never going over 65 rolling as much as possible . I know the jeep has amazing aerodynamics but everybody else is up around 18mpg with more power than I have. I am not throwing any codes. No abnormal gauge signs except my sending unit just going out, but these problems have been there way longer than that.
So as of today I have changed
Plugs 3x
Wires 2x
Distributor Cap
Rotor Bug
O2 Sensors
Seafomed it the last three tanks.
All the fluids in the jeep.
I dont use ac. Just the windows up or down to let enough air in.
I drive slow never more than 65 on highway even when 70 is speedlimit.

What else can be wrong with the jeep? I am not that great with the jeeps yet, but this just has a few of my friends and I a little stumped as to why this is happening. I would appriciate any help that can be thrown my way.

double_ot_xj

actually I have no idea. im not getting that great of milage either. around 12-13 if I baby it. I'm going to watch your thread to soo what kind of problem your having. I think I need to do an extencive tuneup.

Bama91XJ

are either of you running rich in gas?

Like Smelling it when you are sitting still in traffic or when you are behind the jeep?

lilredxj99

Check the regulator on the fuel rail... pull the vac line off and check to see if it has any gas in it... if so replace it. I have seen fuel press reg leak and still hold good fuel press.

purplexj

maybe check the injectors?

kswiencki

this might sound bizare, but check the ccv breather, vaccuum side.check both ends for clogging. and check the throttle body... ive seen real dirty ones create bad fuel mileage.

4.0cherokee

Sweet maybe This will help you save some money.

Yea I would say it is smells a little rich.

Where would this hose be?


We check those yesterday. If they are the one that go from the head over to the air box. We can hold out hand over one and it doesnt kill the engine, just buiils up preassure until you release, and my TB is clean because I ran over 1/2 a bottle of seafoam straight into it, but it was clean and shinny before that.

dirtbiker117

x2 on watching this thread. Try pulling your spark plugs and see if they're all black - carbon fouled from running too rich.

Bama91XJ

Have you noticed a performance change since you engine is getting flooded in a small sort?

4.0cherokee

Just changed last night again. WHen i put the platinum 4 in there they had a lot of build up. Changed to champions about 1.5k ago and then changed them last night and I didnt notice a whole lot of build up.

Yea It is not as stong as it should be. I have to give it quite a bit of gas to get up a hill. It cant really maintian 65 at all. I am going to change injectors this week to some ford 5.0 injectors.

4.0cherokee

Ok injectors are on there way so. I will post what happens when I get them in.

UserID6095

Thinking a leaky injector? What size/color Ford injectors did you get?

wyatts95xj

i have a 95 with only suspension mods nd m/t tire nd i get 10mpg local, 12 highway if im lucky. i kno my jeep has almost 220,000 on it but i just kinda thought that was the mileage jeeps got.

Crawler374

check your air filter. May seem odd, and i may be wrong, but if your filter is wet, packed with dirt/mud, oil..etc - it can starve the engine for air and make the engine force more gas into the engine. you don't have a gas leak do you?

4.0cherokee

No gas leaks. KNN airfilter a little dirty, no mud or water on it. I cleaned it out just needed some of there fluid stuff. It isnt dirty enough to be doing this though. I got the 19# orange toped ford injectors. They were on ebay for 31$ shipped. There are a few more sets right now for like 20$ that end today.
these end today
http://cgi.ebay.com/ebaymotors/ws/eB...ht_6493wt_1165

I also picked a high flow cat so after i test the injectors to see if that was my problem I will just go ahead and throw it on for good measure.