I might have just posted this in the wrong place.....sorry.
I've got a 1989 4.0. Does anyone have a tip on how to remove the top bolt on the ECU? I can't see how.
Thanks, Steve

 

10mm ratcheting wrench. Correct section. I never reinstall that bolt either.

 

Thanks for that. Through all the years of acquiring tools I've never needed or looked into a ratcheting wrench so it didn't come to mind. And I've already sworn (as I have so often since this beast started dying on me) that if I get the top bolt out I'm dropping it off the boat in deep water.

 

Ratcheting wrenches are the cat's meow. Gotta have them.

Why are you removing the eCU? It's not a common item to fail.

 

Just checking connections according to your 'Renix Tips'. I have the chronic 'Jeep just dies' and now 'starts up and dies'. Been following all threads and fixes but no joy yet. CPS is new, MAP checks out, TPS voltage tested low so replaced it yesterday & cleaned throttle body & stepper, checked/cleaned grounds & relays, cleaned IAC valve, ICM contacts. Could be fuel pump. I hear the pump at key on and when it quits I can get a 'squirt' of fuel from the test port....not sure how much should come out. I'm going to check for possibly vacuum/air leak.

 

Never a "bad" idea to refresh the ECU connections.

But, a "squirt" of fuel? Is it high pressure?

What voltage are you getting from your new CPS?

Snug up your intake bolts and check for vacuum leaks just because it is good to do. Not your dying issue but needs to be done.

 

First of all thanks for the helpful replies. I've never had a vehicle that I couldn't fix and I'm gritting my teeth. I had the CPS replaced a few years ago and assume it was after market so I got one from our Jeep dealer about a month ago. I just crank tested it and got .2 ac volts but it started right up??? While it ran before dying I spayed around throttle body/manifold and all vacuum hoses with no change in idle. It finally did die so I waited 30 sec. and it started right up. The idle went high, then dropped but it stayed running??? The new TPS has 4.98 dc reference voltage and .85 output. I'll get under it today and snug bolts. The 'squirt' from the test port was under pressure just not much fuel and I don't have a pressure gauge. BTW, when I said IAC valve I meant IAT sensor on the manifold.

 

Check to see if the connectors at the fuel pump ballast resistor are good and tight.

 

Did that and most everything on your list. After my mini success yesterday I let it sit a while, went out and it wouldn't start. Poking, prodding, disconnect/connect, jiggle...nada. I decided to refresh the ICU to coil contacts AGAIN with emery cloth, contact cleaner and DeoxIT. Bang, started right up and stayed running. I repeated for the rest of the day with no problem....even went out this morning and it starts up (but still skeptical).
One other thing. At the time I noticed the ICU sits on a bracket bolted down so I backed the bolts in and out. I will assume the ICU body is grounded and wonder if you think this bracket could be another critical 'ground refresh' point. Anyway, test drive today.

 

Keep me updated on this please. Pete

 

It does have it's own ground to the dipstick stud. Just on GP though, I'd brush off the mount points. Well done Btw, nice thread, hope you got it!

 

Ground is in fact g104 dipstick tube stud.

 

Well, right now I have a smile on my face. Jeep ran just fine today; stops , start ups, normal service, just like old times. I think I've found it but I've heard those words before.
Picked up some dielectric grease and went at it when I got home (ICU contacts, connectors and all mounting bolts). Still intrigued by a possible grounding through the mounting bracket but maybe the DeoxIT help with continuity. I didn't use it the first two times.
I'll give it a few days and report. Thanks, Steve

 

I admit I got lost in the acronyms! The ECU (the puter'), grounds at the dipstick. The ICM has a black wire for ground. My diagram does not show where, but if it grounded at the ECU I bet it would have shown that. I would want the body of my ICM/coil assembly well grounded do to the secondary business. I guess that's over my head, but it it's giving me 40,000 Volts, I'll give it a ground!

 

See post #12 about where the ICM grounds.