semperfi1371

Okay at a loss. Started fine this morning but had a slight miss which was new but nothing terrible. Took kid to school, went for coffee started again got home killed it checked plug wires and restarted...all good. Went in & futzed around for the day, 6 hours later wont start! WTF? Has spark at the coil and the plugs, 30+ psi at the rail while cranking, coincidentally the psi will drop back to zero as soon as key is released, but that is another day as I don't think its the problem here, checked cap & rotor both are new & good, checked all plug wire connections, etc. Nada! Sprayed starting fluid in TB, nothing, not even a rumble! Anyone have a clue???

Recent work done: check valve in fuel line (100+ miles back), new CPS, new cap, rotor, wires & E-3 plugs, newer fuel filter (within 5k), injector swap w/ new filters & O-rings (300+ miles ago), new pressure regulator, new starter solenoid, new negative battery wiring, new vacuum harness.

I'm stumped, but I need this thing to run! Just had knee surgery,Ive got therapy and Dr., plus I'm a single dad & it's all I got to get the kids to school! ugh..

Any and all help is readily appreciated!
1990, 4.0, auto, 375k

EVcherokee

Well for starters if you installed a check valve it's not working if your pressure drops back down after turning it off. There might be something going on with the fuel system, so don't cross that one out yet.Try pulling a spark plug, diconnect the coil and try starting it, you should smell gas.

Are you %100 you have spark? putting starting fluid down the bore would at least make it rummble if you had spark. Have you pulled a spark plug boot and had one of your progeny turn it over to watch the spark? Figuring out what the problem is will allow you to figure out how to fix it. Keep us updated

semperfi1371

Hey EVCherokee, Thanks for checkin in, I meant to update this yesterday but had my hands full with this...anyway, yes you are correct about the check valve, there is something hinky there, but its the least of my concerns. I'll be replacing the pump in the coming months either way. Yes, I'm 100% sure I have spark & fuel...I also am 100% sure I have a blown timing chain! argh! Not that its the end of the world, but having no other street legal vehicles & the cj & tj both out of commission, this is not what I needed! Fortunately, the Chicago area is experiencing a mild spell of 60º & 70º weather so walking ain't so bad! haha! The biggest issue is the fact that NOBODY carries the timing set in stock, a minimum of 5 days to get it. The only place that has it, Rock Auto, charges $80 for next day delivery & they're in Illinois..WTF? Well, JeepOEM had it & I hope to have by Thursday before the monsoons begin...so, I wait!

semperfi1371

Well it's been almost 3 weeks now and it finally started yesterday. Here's what has happened ( sorry for the drawn out post):
I was driving it on first cold morning of the season and all was good, noticed a "ticking" but figured it was just lifter tick due to cold and no warm up, something like that so when I got home I popped the hood took a look-see and didn't see anything out of the ordinary. I killed it let it set & restarted, no problem. I went inside & when I went back out 6 hours later, no start, it just cranked and cranked. I had crisp blue spark and fuel so I ruled out CPS, coil, ICM cap rotor & wires. I don't recall why but we determined it was the timing chain at some point. I replaced that and when all was said and done she still wouldn't start! Well after futzing around for a week I borrowed a compression tester and I had 30psi! I pulled the front apart again and found I was a few teeth off, I lined up the wrong mark on the cam sprocket, so I used centerline procedure with a dgree wheel to dial it in at TDC. I started it before putting it back together JIC and she roared to life! Great I thought! Well, I buttoned her up, turned the key and....no go, just crank crank crank! WTF? Spark-check, fuel-check, compression-check...Though I never messed with it, I decided to index the distributor. That was last weekend so Tuesday, I got out there and jerry rigged a remote start and while holding WOT I managed to start her she idled a few minutes and stalled. No stumble no hesitation, just stopped. Turns out I ran outta gas! Got a can of gas put that in, now the battery is dead! ugh! So I get a jump, idles a few minutes so I decide to take a drive to fill her up, well I had yet to put the radiator bracket back in so I couldnt clse & latch the hood so I took it slow, but it seemed ok. As I got closer it seemed to be running rough and when I pulled in she died! I filled it up and it wouldn't restart got a jump and still nothing. So I strapped her up & yanked her home where I find that the heater hoses and coolant tank are frozen solid! I forgot I had put H2O in there temporarily so I could run a flush! No cracked block or radiator I think I was maybe 3/4 full so there was room for expansion. So I threw a heater under the hood and put a trickle charge on the battery last night and am deciding on my next steps...
fuel pressure is 31psi running
IAC?
TPS?
CMP?
O2?
MAP?
ECU?

Any thoughts, suggestions, ideas? Any and all are welcome! Or you can tell me I'm an a**hole & good luck, too! haha Seriously though, I'm out of ideas myself and I'm about to throw in the towel and dump the POS but I promised her to my kid next semester when she can have a car on campus so I gotta get her fixed up right. If you have a thought or something I have overlooked in my haste (it's pretty cold out) please chime in, thanks!

New:
timing chain (centerlined and degreed with wheel)
plugs, cap, rotor, wires
Ford 19# injectors
Battery cables
new grounds with 4ga cu cable, cleaned up ground points, + added battery to chassis & to ICM/coil grounds
cleaned all connectors & used silicone grease
CPS
Harmonic balancer

tested with analog & digital multimeter:
CMP
CPS
coil
ICM
injectors
battery (its new, low but takes charge)



I have a spare coil, ICM, fuel rail, regulator & pump, plugs, cap, rotor, wires, injectors



1990, 4.0, aw4, lots of miles,

freegdr

did you check injector pulse

semperfi1371

Yes, all injectors are pulsing, all are good. As a matter of fact, I just had it running again, idled about 10 minutes before stalling out. I believe it was running pretty rich though...

Bustedback

I think 30 psi is kind of low for the fuel pressure.

semperfi1371

I don't think so, if I'm not mistaken, 31psi is the ideal pressure for this Jeep so I'm very close to perfect there. I know that I will be replacing the fuel pump soon, the internal check valve is toast as is the in-line check I put in. I have a new Bosch, 69302 I think? and sock strainer that I got on Amazon for $75, but I have a full tank of fresh gas so I'll be waiting til I'm under 1/2 tank. I've really checked everything now, so I'm at an impasse. I know a guy with the 1700 tester, I'll have him by Monday or Tuesday and see what that shows if anything, its kinda useless really. I think in the morning I am gonna pull my MSD 6200 off the CJ and wire it in. It will give me a series of sparks at each cylinder for 20º of crank rotation, thats a lot of spark plus its white hot and works with the stock coil and ignition in the Renix. It's worth a shot & I have nothing to lose but 15 minutes of my time!

ol"blue

Sorry, I don't know anything about the Renix system, but I'll post this hoping it may help. > http://www.lunghd.com/Tech_Articles/...iagnostics.htm
Good luck.
Dan

EVcherokee

If you haven't already, suspect or replace the O2 sensor. The motor ignores it until your warmed up. Even if you go for a little drive, like in your first post, then let it sit(futz around), the motor can think its warmer than it is, because the coolant isn't moving anymore.

I'd also be mad-******* your coolant temp sensor - the one for the ECU under the intake/exhaust, forward of the knock sensor IIRC. The gauge sensor is a one wire on top of the head, and the ECU on is a two wire sensor...I think. Your air charge sensor(air temp sensor) on top of the intake could be giving you problems too.

Its starting when its cold right? For about 10 mins?

semperfi1371

We're on a similar wavelength EV, these are thoughts I have had as well, as well as my MAP sensor. I have a few spare MAP sensors, off F1 & 250's IIRC that snap right in, might work for this one too? As for O2, coolant & AIT, I found them & a MAP on Amazon, placed the order it's $78 for all 4 with free shipping which is an outstanding bargain IMO. So with 375k on the clock, they're due, its been a few miles since any were replaced.

Additionally, I fired it up again today and I seem to have a dead cylinder, #4. It has 120psi compression, fuel and spark but if I pull that wire at idle there is no change. I am running very rich and there is misfire, rough idle. Also a note, I have a great deal of pressure coming up into valve cover! I have never seen anything like it before, the oil is actually bubbling out through the cap. If I open it and leave it sit on there it literally bounces up and down while cranking & not due to vibration but pressure, weird right? I have 120-130psi across the board on all cylinders...

Just had a thought on odd valve cover pressure, valve seals, maybe? Seats? Though wouldn't that drop my cylinder compression? If that is the case, I can pick up a head from a '96, I think, gratis. I've never done seals while the head was on engine in car, I don't know how difficult it is or if it can be done even, though I assume it can. Neither task I would wish to undertake in the winter elements here in Chicago, my condo has no garage lol Oh how I wish this had happened in Courthouse Bay , 70º there today!

This truck ran like a top up until 3 weeks ago, I wish I knew what went wrong where, it's driving me bat ****! Ive aged 4 years in that time, though my mind is getting a workout which may prevent Alzheimer's and dementia as I understand it!

Sorry for all the emoticons, I just always wanted to use them! So dumb...hahaha

semperfi1371

Thanks Dan, I appreciate the link,unfortunately I am far too familiar with his webpage! lol

EVcherokee

The renix system only uses the MAP sensor when its in warm up mode and when you mash the skinny pedal. Once its warm it ignores the MAP sensor and relies on the O2 sensor

When you pull the wire, is there spark coming out of the boot? might be a bad plug too. When ever I drop a plug on the ground, I suspect it will be bad because sparks can stray through the tiniest cracks in the insulator. You possibly could have a broken ring, but I've never heard of a motor compression testing ok with a broken ring. However if you have a score in the cylinder wall that is near the bottom of the stroke, it would bleed off a little pressure to the crankcase and compress the rest giving you 120psi at test...just a thought..

If your seats where bad, your wouldn't have such great compression. It could be valve seals on the exhaust side, and they can be changed while on the motor, but its not fun and if you mess up, you risk dropping a valve. At 375K I bet your valve guides are as loose as a *****, so replacing the seals are just a temp fix. Bad seals also wouldn't explain the rich A/F mix, but a bad O2 sensor would. Before swapping heads, figure out whats wrong first.

My advise at this point is to get coolant in it ASAP and see how that helps, it will also thaw your block out if its still frozen. Once that happens leaks at the freeze plugs wouldn't surprise me. If pull the valve cover, you might be able to see whats going on too. I've never done it on a 4.0l but you could try starting it with the cover off and seeing where all the pressure is coming from. Have lots of shop towels on standby and be ready for a mess.

At 375K its probably time for a rebuild, so be ready for that too, especially because it was running fine then took a dump.

semperfi1371

Yeah, I was thinking about this having to do with the hard WOT start condition I've had prior to warming up.


This happens with any plug, I have a few dozen. I will be digging further into this today I hope, given the time.


I looked into this last evening & see that it would be quite the chore if I went this route, we shall see. I've got the O2 sensor on the way, hopefully in the next day or 2, along with MAP, IAT & CTS.

I have had a space heater & block heater on the motor the last few nights to deal with the coolant issue as I haven't been able to drain the H2O yet & replace it, I've had blocks freeze here & when I was in the service while stationed in Alaska, not fun or amusing.

We ran it with the valve cover off on first start up after centerlining the cam, I didn't see anything going on that was blatantly obvious, but then I wasn't looking for anything out of the ordinary. I can say with the mileage, I was prepared for a major overhaul next summer. When I had the valve cover off, having a great deal of experience with Chrysler A & B/RB blocks which are notorious for rocker arms loosening at higher mileage on the rocker shafts, I checked every rocker arm bolt, removing them and torquing them down with moly on valve tip & push rods. I saw no telltale evidence of loose valve guides or seal issues. Again, I wasn't really looking for these problems either so they may very well be there.
I know this is a great deal of mileage, surprisingly its in very good shape & has been meticulously maintained since new, so rarely does anything major happen. As I said though, I am prepared for major rebuilding, but it can't happen til spring/summer. I won't allow it lol but everything is here and ready, I just don't want to start yet so I have time to have one of my other vehicles road legal first or at least covered and heated.

shoytjr

I had this similar problem with it not starting. If primed it would start and run. let it set for a while and it wouldn't start again. Checked TPS, Crank sensor, Cam sensor, fuel pump relay and changed the fuel pump. Did not solve problem. I finally un coupled the wire harness at the fire wall and found the grease used by the mfg turned to tar. Cleaned the connections and re lubed. Problem solved. "SO GO THERE FIRST"