Help! 1997 Cherokee 4.0L

[troy808]

Hi, I need some help. A friend of mine has a 1997 Cherokee 4.0 L.
At first he tells me that at around 50 mph his jeeps started to spudder. Now, this was happening for about a week. Now he tells me that he filled up his fuel tank only for the thing to run alomost empty in 2 days with three short rides. No visible leaks according to him. Also, he claims that he loss alot of power going up hill. He also tells me that it would not shift while coming up hill untill it hits the down grade. I can't figure it out. can someone please point me in the right direction.

could it be his plugs are fouled or a filthy fuel filter.


Thank you

Troy

[badron]

Do the basices first. Check all vacuum lines. Get some contact cleaner and go over all plugs under the hood. Check timing. Timing is set by the computer I think. But if the Dis does get turned way off it can course problem. Check plugs, wires, coil. Open the hood at night and watch for firer works off the wires. Check the clutch fan for free spin. Last but not least tie a big dog by the gas door. I myself did borrow a gallon or two when I was young. Luck

R Robinson

[tblack]

[quote=troy808]Hi, I need some help. A friend of mine has a 1997 Cherokee 4.0 L.
At first he tells me that at around 50 mph his jeeps started to spudder.

Troy;
The shifting sounds pretty normal because the AW4 downshifts and stays downshifted until he lets off that pedal at the crest of the hill. It's supposed to do that so it gets him over the hill. He's probably got the pedal to the floorboard out of apprehension that if he doesn't, he's not going to make it. It's hard to beleive there is no fuel leak though. He must be smelling raw fuel somewhere and my estimation brings me to conclude it is in the fuel system. There are a number of things in the system that could be malfunctioning. Probably not the pump because it is pumping fuel out of it otherwise without a leak, we know it is not just draining on the ground. The fuel filter is a long shot too. I would begin at the injection system. Check for leaking fuel lines and the injectors that may be leaking onto hot surfaces during the drive and evaporating before they hit the ground. He needs to open the hood and rev the engine about the same RPM that would represent going 50 MPH and see what is leaking out. He should not be driving it if after only a few miles the fuel is gone. Either someone in his neighborhood is stealing fuel at night from him or he has a dangerous problem. Especially if he cannot find the leak. That means the fuel could be going anywhere and my good guess is that it's coming out of either the fuel lines near the injectors or the injectors themselves.

tb

[troy808]

The problem still persist. I helped him change spark plug, wires, cap and rotor. Plugs were black as if running rich. a whole buch of black stuff came shootin out his tail pipe. It ran rather smoothly for a little while until he test drove it and went up a hill. Now the the cherokee can't barely go over 10mph. hmm..I will be changing the fuel filter today and try to pick up a pressure guage to take fuel pressure reading..and will keep you updated.

If you have any other thoughts ..please feel free to post ..and thanks for the replies.



Aloha



Troy

[gtmud]

Black soot is a good indecation of a rich burning engine. I would suggest pulling the injectors and getting them tested, sounds like he has a couple injectors that are leaking allot.

[troy808]

I took a fuel pressure reading today and it is reading 50 psi. I also took the Jeep on a test drive and it seems when cold to warm temps it runs ok. But, when i tried to get the Jeep into higher speed it's like the transmission is stuck in second gear and would rev up 4500 rpm and keep over reving, I tried letting off of the gas the back on and it shifted. Then when I got back to base (Schofield Barracks) I guess the temperature was about 200 and thats when it really started to spudder and fart. hmmm...

Gt When I pulled the plugs it seemed that all the plugs were covered in soot...could it be that all the injectors are bad? Also would this cause the transmission not want to shift into 3rd and 4th or overdrive?

My friend doesn't have alot of money. so, im just trying to help out.

I CANT FIGURE IT OUT!!!

Could it be timing?


Aloha , Troy

[weezzle]

You could check out my post:

96 Jeep Stops taking gas around 3000RPMS

I really hope that this isn't your problem b/c it's not a cheap fix.

FYI:
The fuel pump module controls how much fuel it pumped to the injectors from the fuel pump and it can only be purchased from dealer. Or junkyard if you can find.

Again I am no expert. just my

[ops5]

The problem I had was my tps was bad, and that caused my tranmission to "stick" in gear and not shift, along with some generally rough running of the engine. It seemed like a fuel thing, but wasn't. Of course, you could have a different issue, but just putting out there what I had.

Do the code scan if his has the key on/off ability (i don't remember offhand if that year does) and see if there are and issues there. If not, then at least you can rule that stuff out, more or less.

[troy808]

Problem solved...we hooked it up to a cheap scanner and pulled up some codes. Turned out it was pointing to cylinder misfire due to bad O2 sensor. I my post i said that the jeep was shooting out black smoke (soot)...indicating that it was running rich right? But, this scanner some how threw a code saying that it was running lean..now what in the world could cause that?

Well to make a long story short. We changed out the O2 and its running ok now , but still blowin soot from time to time ..i will check timing and get back with you guys.

I would like to thank everyone who responded to the post ..



Thank you very much ...



Aloha



Troy