Hey guys.. Hopefully I am posting this in the correct section...


I need some help diagnosing my 89 xj with the 4.0 inline 6... I need to get my jeep up and running ASAP for hunting trip, in which I would like to drive my jeep to...I Love my XJ and the jeep community and have had tons of fun in the jeep as it has never let me down until as of the last 9 months or so... I want to drive it!!!!

To the problem... I will try and be as clear in describing the symptoms as I can be... I will also list what i have repaired in order to "FIX" the issue..

Jeep starts up great, just like any other Renux ecu jeep... Problem is after i let it warm up for a good 5-10 mins (that is if it doesnt die at least once). I put it in drive and a take off... When i start to give it throttle the engine starts to lose power and sounds as if the engine is staring itself for air or is caughing becasue its pipes are clogged. Backfires a bit as well..

This happened the first time when i was going up a hill and needed the extra power... pushed on the pedal nothing happened, pushed it down some more, still nothing ... Then the sounds of "caughing" "clogging" backfire... .

What I have replaced:

• Spark plugs
• Plug wires
• Cap/rotor
• Fuel filter
• Throttle Position Sensor

But still the problem exists... Anyone have any ideas??? I have checkd the MAP sensor and that is working properly...I just dont know where to go next... Plus it doesnt help trying to find a decent mechanic who actually knows something on craigslist..... ahhhhhhhhhhhhhh

BTW.. I dont have any cats in the exhaust system... so it not a clogged cat...


any light shed would be much appreciated....

 

Its probably a fuel pump. Check fuel pressure.

I'd be careful about mentioning you are catless. Against forum rules, you'll get *****ed at.

 

DId you make sure the boots are all the way on and theres no arching?

 

I think if it was Fuel pump, wouldnt it just go out completely? Since it is an electric motor in the tank.....

Why no cats against forum rules? I live in OR where there are no emmisions.

 

boots? arching? You mean on the spark plugs/ rotor??

Eveything there looks fine..

 

Nope, a fuel pump can seem fine til you put load on the motor, for example when in drive and you are holding the brakes. I've also had vehicles that would run fine when cold, but once the fuel pump warmed up it the motor would pop, studder, and run like ****. Fuel pump just couldn't supply all the needed fuel.

And after a certain year in the early 80s all vehicles were required by federal law to have a cat. Just because you aren't inspected doesn't mean its legal. Its also in the forum rules. Personally I don't care, its on you and your concience. People will *****, though, cuz its polluting the air and such. Like I said, though, its on you, I'm just trying to give friendly advice.

 

definitely sounds like a fuel delivery problem. Check these in order:

1. Fuel pressure at the rail
2. All injectors firing correctly?
3. Fuel pump sock clogged?
4. Replace pump

 

gotchya... Thxs much for the advice... Is the pump located in the tank??

 

ok... Do I have to pull injectors to make sure they are firing correctly? Fuel pump sock... is that the pre-screen on the pump itself?

anyone know about how much a fuel pump is?

 

No just disconnect the electrical lead. The one that doesn't make your engine run worse is the bad one.

Yes

 

pull fuel pump and make sure hose clamps are tight you said it did it when you went up hill ive seen 2 other people have loose clamps mine did this and my clamp was loose mine is also a 89

 

You know about how long it would take to drop the tank and get to the fuel pump?? Luckily my gas light is on right now... so i think it would be a perfect time...

Is there a DIY on here somewhere?

Thxs

 

45 min to an hour. Its not hard. I've done a few on Liberties, too.

For a guide look into a Haynes or Chilton guide, it'll tell you all you need to know and more.

 

The boot that goes over the spark plugs. I have coil packs on my jeep but I had similar issues and i noticed archning (sparks come out under the boot goin to the block). I had similar issues to yours. I also had touble with one of my coil springs to the plug, but checking for arching isnt hard. Its real easy whens it dark out, just look for the spark.

 

I dont have a Haynes or Chilton guide... Anyone on here post a DIY?? Trying to do this today...