1990 no start, has fuel & spark

[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

 

[1987Comanche]

Even though you just replaced the CPS it sounds suspiciously like a bad one to me. My '90 would refuse to start 1x/month and I eventually figured out that was the problem. If you tap the sensor and/or disconnect and reconnect the wires does it do anything?

 

[Stumper92]

I just went through a troubleshooting session on the same year Jeep. Are you sure you are getting a strong spark? If so I would start looking for a major vacuum leak. If you have good fuel pressure and spark, I would say vacuum and timing would be the only things that would prevent it from starting. You might want to check the EGR valve and the plastic check valve next to it. Another thing could be your TPS or MAP sensor.

 

[joe_peters]

If you are getting spark that eliminates the crank sensor, ECU, and B Latch relay.

If you are getting a hot, blue, snappy spark that tends to eliminate the ICM and the coil.

How about spark distribution? Pop the cap, check the center contact, pull the rotor and check it for cracks/damage. If Ok, have someone crank the engine over and see if the rotor turns.

 

[semperfi1371]

Thanks fellas, I appreciate the help and I've found that sadly it is my timing chain...ugh

 

[joe_peters]

Ouch!

Good luck.

 

[semperfi1371]

Thanks Joe! I'll need it I think! I pulled the cover today, after setting to TDC and my cam sprocket was off maybe 20º! WTF? so my cohort and I futzed with that thing for 7 hours and still it runs like crap! I have no idea what the issue is but when I set for TDC on the compression & install the chain and sprockets the cam gear is always off...fishy! So tomorrow I'll be pulling the valve cover back off & attempting to start from scratch. Fortunately I haven't bolted anything up in front yet, I just ran it with 1 bolt in the timing cover to stop oil spray!
Anyway, is there something unusual about the Renix 4.0 compared to the 4.2? Is this normal to be off so much and start? When set at TDC on compression stroke (valves closed, springs slack on rockers) and rotor lined up to #1 on cap, it pops & chuffs. If I set cam sprocket 20º off (at about 2 o'clock) and it starts but runs rough...
I'm hoping I was just frustrated with the degree of difficulty in finding the correct timing set without having to wait a week (nobody carries it anymore) but it still cost $40 extra to have it overnighted by Summit! Do later model chains work? I figure they must, but I wasn't sure, so I didn't try. Besides, I dont wanna get stuck with one that wont work at $75 when the 1990 part was $150!

 

[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 :fuse:
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,

 

[birchlakeXJ]

Back to basics.

So as it sits now, you DO have a strong, snapping blue spark?

If so, you MUST concentrate on verifying that fuel is getting TO the injectors.

Have you used a noid light or some other way to verify that the fuel injectors are PULSING?

That would be my next step.

 

[semperfi1371]

yes, actually I went out just a couple hours ago, it fired right up and idled for about 10 minutes then stumbled, petered out & died but there is definitely fuel getting to the injectors. I tried to restart it but no dice. The battery is now too weak to turn it over, need to pick up a charger tonite or tomorrow

It was running pretty rich though, not sure if that will point to anything. I am really at a loss here

 

[JJacobs]

I have not seen much good said about E3 spark plugs. Do you still have the old ones?

 

[semperfi1371]

I have a set of Champion, NGK, the old ones and the E3. I have swapped plugs in & out during this endeavor due to fuel on plugs. I take a set out, put them in my plug cleaner and another set in. That said, the E3 set has been in there over a year and when they replaced the original Champion set, mileage was increased by 2-3mpg which made me quite happy considering gas prices in Chicago. So to give my thoughts on the E3, those plugs are just fine. My problem here is that I've never had a vehicle that is dependent on so many sensors and electronics just to start as this Renix system is. I am honestly half tempted to yank the whole mess and throw a carburetor & points ignition system in, though that is probably a lot of hot air haha I am however considering wiring in the MSD system from my CJ in the morning. Its easy enough to wire in, uses the stock coil and gives, I believe, a series of sparks that last for 20º of crankshaft rotation for each cylinder which may or may not help with my situation, I don't know, but its free and takes 15 minutes of my time to try it. At this point, all bets are off & all options will be explored! Of course I can drop a 340 or 383 in there too lol

 

[tugalo]

Just a thought.....one of your posts says that the rotor was lined up on the #1 post...it should be closer to the next post (#5?) in the direction of rotation. Distributor indexing?

 

[semperfi1371]

Just a thought.....one of your posts says that the rotor was lined up on the #1 post...it should be closer to the next post (#5?) in the direction of rotation. Distributor indexing?

I was being too general, sorry. I indexed the distributor a few times now it seems, turn oil pump to 11 o'clock, point rotor at 4, drop dizzy in rotor scoots to 5o'clock tighten down so the rotor electrode has just passed #1 and centerline pointing at approximately 5 o'clock position. 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. Also a note, I have a greatm 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! I have 120psi across the board on cylinders...

Just had a thought on 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!

 

[cruiser54]

I'm curious about something in your first post. You installed a fuel line check valve? Why, and where?

 

[semperfi1371]

I'm curious about something in your first post. You installed a fuel line check valve? Why, and where?

That was some time ago, but yeah I put one in when my pump wasn't holding any pressure. it was determined it was bleeding back into the tank & that the integral check on the pump was faulty. The check was a cheap alternative to a new pump is all, nothing more. IIRC, I installed it in the line between the filter & the engine. It has since stopped helping & I have a new Bosch pump ready to go in. It has nothing whatsoever to do with my current issue though truthfully. I have a constant 31/2psi while cranking and running. Volume is excellent as well at just over 1l per minute.
I will be installing a new O2, IAT & CTS this week, which I just ordered, and then the pump if I can burn off 1/2 gal or siphon it off to another car...alas my others require 92 minimum, I believe I have 89 in this one

 

[IH392]

Maybe the fuel injector on number 4 is stuck open, causing you to flood out. Do you have a spare injector to swap in?

 

[joe_peters]

I guess the key here is to try and determine the exact missing element when it dies and won't run.

Elements:

Compression
Spark
Air/fuel mixture
Injector pulse

Compression doesn't come and go, so we can a**ume that isn't the missing element.

Spark is present when in the fault condition?

Getting an injector pulse when in the fault condition?

PITA but you need to go back over all the basics, don't a**ume anything.

If the battery can't deliver 9+ volts with the engine running, engine management goes in the toilet, so you need to get it fully charged and a load test wouldn't be out of order.

Don't forget to check the vacuum line from the throttle body to the MAP sensor, if it gets displaced it will run rich and crappy.

 

[87manche]

to add to joe's list

check the grounds, every single one, and just go ahead and replace that braided ground strap from the firewall to the head.

 

[semperfi1371]

to add to joe's list

check the grounds, every single one, and just go ahead and replace that braided ground strap from the firewall to the head.

I snatched a truckload of Mil-Spec 2-8 ga copper cabling from an older M728 CEV and used a bunch of it to replace my ground connections on all my vehicles, it was free lol So on passenger side of the block, at dipstick bracket: I acid cleaned the block; installed a new 2ga ground cable from the battery to block; 4 - 14ga black ground wires from harness; on 2 eye loop connections, combined to 1 new copper connection; new 4ga ground strap added from driver side head to firewall; added 2ga ground from battery to chassis; new 8ga cable from ICM/coil to battery; 8ga from starter relay to battery direct ground.I also cleaned up the driver side fender & harness grounds there as well. All new connections are soldered, not crimped, with pure copper heavy gauge eye loops, I then "painted" these connections with liquid electrical "tape" & covered them with heat shrink tubing and the asbestos sleeves removed from the tank with the wiring. :shhh: I know, bad stuff but it was in great shape so I used it. I haven't checked any of the grounds under dash in cab yet, though I feel that they aren't part of the issue.