'91 XJ Help plz

R Q said:
Is the IAC supposed to move freely or is it somewhat rigid? We put in a used unit from junk yard.
Will start over tomorrow and rec
Click to expand...
no should be still and not moveable with your hand. sorry to hear TPS didn't help.
so no matter what u give it, it dies and won't rev up either? does the jeep have keyless entry/alarm? still thinking of what causes them to shut off right after startup.....................
 
John Fuller said:
no should be still and not moveable with your hand. sorry to hear TPS didn't help.
so no matter what u give it, it dies and won't rev up either? does the jeep have keyless entry/alarm? still thinking of what causes them to shut off right after startup.....................
Click to expand...
I can spray ether and it will chug on for a few extra seconds. No keyless entry.
 
im around most of the weekend. I live in Steele Creek near hwy 160/49. Hit me at the number below.
 
Update. Installed new fuel pump assembly as the old new one was destroyed upon installation by the idiot PO. It runs a little longer but still only a few seconds but the gas gauge now works. We can actually get it to rev if we pump the gas just right, then it dies. Fuel pressure is good . Grounds have all been taken apart and sanded and reinstalled. Spark looks good on coil wire and all plug wires.
It starts to run and then dies like something is shutting it down. I'm thinking the junkyard IAC is no better than the one that was in it. If I put gas or ether in the throttle body it may rev for a few seconds but sounds like something is telling it to shut off the air.
Thoughts?
 
try bypassing ballast resistor (if it has it) some 91s had and some didn't...it's that little ceramic thing next to air box on DS fender well...the signal comes from the starter relay which is right by the battery with all those wires going it....also i don't remember but is the cam sensor in distributor known to be good...you can test em with ohm meter...last on my thought would be ignition switches are known to melt also on some of the terminals and can loose signal after starting in the run position. sorry man, it's hard to diagnose this over the web..forgive me if i cause you to spend any not needed money on parts and such.
 
Edit: We will replace the Cam Sensor before moving forward so the following isn't applicable until we do that.

Are the ECM's between the Renix and Bosch systems basically the same, ie., shape and connectors? Our Jeep is a '91 by title, manufactured in 08/90 but has a Renix distributor.
Knowing that we had a '91 Cherokee, I got an ECM from a '94 with same running gear and we finally got spark and fuel. Before that we had nothing.
We tested the Cam sensor per interweb directions for the Renix and we got no pulse nor volts. It said to check continuity between posts on the wiring harness but so far tests are inconclusive because the wires don't seem to be in the same color combos as the positions on the ECM connector diagram state where they should be. That made me think that even though the Jeep is a '91, and is supposed to be Bosch, but has a Renix system so that got me to wondering if we got the wrong ECM?
I'm sure these ECMs can't be compatible but the harness fits the same between the two.
Thoughts?
 
Last edited:
R Q said:
Edit: We will replace the Cam Sensor before moving forward so the following isn't applicable until we do that.

Are the ECM's between the Renix and Bosch systems basically the same, ie., shape and connectors? Our Jeep is a '91 by title, manufactured in 08/90 but has a Renix distributor.
Knowing that we had a '91 Cherokee, I got an ECM from a '94 with same running gear and we finally got spark and fuel. Before that we had nothing.
We tested the Cam sensor per interweb directions for the Renix and we got no pulse nor volts. It said to check continuity between posts on the wiring harness but so far tests are inconclusive because the wires don't seem to be in the same color combos as the positions on the ECM connector diagram state where they should be. That made me think that even though the Jeep is a '91, and is supposed to be Bosch, but has a Renix system so that got me to wondering if we got the wrong ECM?
I'm sure these ECMs can't be compatible but the harness fits the same between the two.
Thoughts?
Click to expand...
hey bud, yeah you have that weird year model where they started to change things over but if it's a Renix Ignition system, than you need a Renix computer...which kinda would make sense as far as sounds like the Computer is shutting down the system once it starts if the computer you have in there is newer. is your computer mounted under the dash or by the air box?
 
well the ECU by the air box makes it a HO computer setup...all the renix ecu mount under the dash. i wonder if the computer you got from that jeep had security alarm which would then shut down after startup..try your original computer again. it really does sound like the computer is at fault here. (that little wire going from the back of the head to the firewall isn't broken is it...i've seen those cause no run issue before when broken in half laying on manifold) i just went through this very same issue with another friend over the phone and week later turned out to be ECU related...very frustrating to deal with i know!
 
I tried a known good ECM this morning and it fired up and ran! So we wasted a lot of time and money. If the junkyard ECM hadn't of made it try to start I guess we would have figured this out sooner. Ok now on to whatever else this little beast needs!
Thanks for the help.
 
dang man...glad to hear it running. sucks you had to go through so much hassle but at least now you have several good parts to make it more reliable! enjoy the rest of the "build"
 
Back
Top