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I have changed:
coil
crank sensor
cam sensor
plugs
fuel filter
fuel lines
cap/rotor/distributer
plug wires
What it does:
cranks very well
has spark at the coil wire
when i crank it, it sparks once then loses spark after that
but it continues to crank.
It will not fire and run.
what do i look at next?
thanx for the suggestions.
Stukboy
This is one of those strange ones which could be a computer problem. Would be nice to swap in a salvage yard computer to see if that resolves it. Only other thing I can think of is the ignition switch.
Was there any work done on this and the no-start happened AFTER that, or did this just happen all of a sudden? If any work done, of course you must go back and look at the work performed.
It was suggested to trace the wires from the cam sensor to
the computer and check for continuity(sp)
also from the coil to the computer.
It juststarted all of a sudden with no warnings.
Thanx for the suggestion.
As for the computer don't they need to match??
I mean there are a lot of models in 92 with differant combos.
Don't I need one from a XJ with the same stuff as mine?
Stukboy
Yes, you need to have a specific computer for your year/transmission, etc. Can't tell you exactly which ones will work, but a salvage yard should have that information.
The problem I see with a continuity problem is that you mention that it sparks "once". If the wiring was OPEN, you wouldn't theoretically even get that.
DUDE this sounds EXACTLY like my 94 ZJ 4.0/auto. I have even done everything you have done. Mine refuses to fire, but also sounds very healthy when cranking.
-coil, wires, plugs, cap/rotor.
I also took apart the throttle body and cleaned it with TB cleaner and a toothbrush, then threw on a new gasket. I also replaced the fuel filter, fuel pump relay, and ASD relay. AND I replaced the Crank Position sensor on the trans. When I replaced the cap/rotor, I removed the Cam Position Sensor and cleaned that with electrical cleaner. I unplugged every electrical connection and added some dielectric grease.
OBD1 XJ's and ZJ's are almost identical, in fact I believe ALL 4.0/ auto/ OBD1 jeeps use the same computer.
I am unbelievable frustrated with it, but I know I will be happy when I get it running good. I bought it from my friend for $200 after it just left him stranded randomly after years of reliability.
SO is there anything that worked for you that I should try? Im about to just grab a used computer from the Pick and Pull, I heard there known to go bad on these early 90's jeeps.
Do you get fuel??? If not do not forget tho check that stupid resister(long white block with two wires to it) on your fender. I had a bad one and ended up saying ta hell with it and bypassed it. This was on my 89' but I am pretty sure the 92's still had them, the one I worked on did anyways.
Let's see,
orange--Yes I have fuel pressure at the rail and yes it holds. I run a fuel cell with a Holly fuel pump in the "framerail". It's very easy to hear it running and it runs strong.
The battery is brand new and hooked up to my Expedition so I don't kill it while trying to start it.
magimerlin--I replaced the resister already.
birchlakeXJ--True on the continuity!!
austinaubinoe-- I replaced the crank sensor, I also cleaned the throttle body but didn't take it apart.
I sprayed cleaner in it while trying to start it. That didn't even work.
I guess that settles it, time for a new,to me, computer.
Stukboy
PS: OK, I just found an exrta computer in my garage for an XJ. There are no marks/tags telling me what year it is from.
Since I have parted out several in differant years I don't remember which one its from.
Will I kill anything if I hook it up and it's from a 95,96,89,88,94?????
Yes, these are year XJs i've parted out.
Thanx again.
You need the same part number as the one in your XJ. I used to have a 91 with the same problem. We (friends) wound up tring everything possible including replacing the dizzy. Wound up calling the dealership with the vin and the wrong computer was in it. Got the right part number one and she fired right up and ran like a top. I would look in the yards for one with the same options and part number as you have now.
Have you cleaned the HC coil input contacts underneath the HV coil. and cleaned the ICM contacts that connect to the HV coil? Also have tried swapping out the ICM/HV coil assy? Checked the wiring and signals to the ICM?
How about the engine to battery ground? The engine must be grounded to get more than one spark. ICM is and electronic module too!!! It may be dying.
Have you cleaned the HC coil input contacts underneath the HV coil. and cleaned the ICM contacts that connect to the HV coil? Also have tried swapping out the ICM/HV coil assy? Checked the wiring and signals to the ICM?
How about the engine to battery ground? The engine must be grounded to get more than one spark. ICM is and electronic module too!!! It may be dying.
What did they replace the ICM with? I thought the ICM & coil was the same all the way till they went coil packs in ? Haynes says nothing about eliminated the ICM till year 2000?
Edit: I checked AZ online, no ICM listed, so did they move the ICM into the ECU in 1991 with the HO engine, and the switch from the Renix to the Chrysler ECU?
What did they replace the ICM with? I thought the ICM & coil was the same all the way till they went coil packs in ? Haynes says nothing about eliminated the ICM till year 2000?
Edit: I checked AZ online, no ICM listed, so did they move the ICM into the ECU in 1991 with the HO engine, and the switch from the Renix to the Chrysler ECU?
The also moved the voltage regulator to the ECU in 1991 as I understand. I wonder if that is why the RENIX ECU last forever and the Chrysler ECUs fail?
ICM was indeed done away with after '90. dizzy was done away with after '99.
I'd have to say you should test the sensor - wish I knew of a better test for the '91-'01 sensor. An oscilloscope would show the signal quite nicely if you had one, makes me wish more people had them on hand. I think it was McQue that posted up a pic of the signal he captured from his '91-'01 CPS using his oscilloscope a while ago.
