JefCooks

Not really. I replaced the coil with the original working coil and the same thing was happening. I've read about the Crank Pos Sensor reading right but still not working so I replaced that and it fired right up but died about 30 seconds later. I hooked up a fuel pressure gauge and am getting steady 32psi while running, no excessive leak back with engine off and pressure actually went up as the engine died because of vacuum. I checked resistance on the MAP and Throttle Pos Sensor, both were good and no dead spots on TPS. I just ordered 2 NTK crank sensors because the symptoms improved with the new CPS but since it's still dying I suspect it was a dud. I also ordered an 02 sensor because I don't have an oscilloscope to test mine and even if it's good, a spare would be nice. I'll report back later this week.

If I’m ever out east I’ll let you know and we can talk about a swap lol. As far as the boat rack, if you don’t find some built in supports when you redo the roof then it probably mounted to the structural angle iron. Congrats on the rad find!

It’s in my signature but it’s a ‘92 4.0 AW4 4x4

Hi Everyone, I tend to overshare and explain the entire situation in my posts and they can get a little long so if you want the short version, skip to the next paragraph. Over the weekend I was leaving work and my truck wouldn't start. Typical crank no start. I made it to work perfectly fine and had not been having any issues with it so this was really out of the blue. I towed it home and started doing some diagnostics. Air filter is fine and it's getting good fuel so it must be a spark issue. Immediate thought was CPS sensor but it tested good with the multimeter. So I pulled a boot off a spark plug and cranked, no spark. Opened up the distributor cap and everything in there looked good. Tested the wire from coil to distributor and it is only getting intermittent signal. Took the multimeter to the ignition coil and it's getting proper 12V constant and 10+V signal. Secondary resistance is right on but primary resistance is low (.5 Ohm vs .85 Ohm for aftermarket coils). The ignition coil is ~13 months old and I splurged on the Accel coil thinking it would last longer and give better spark, I was wrong. So I got out the 30 yr old oem coil, plugged it in without removing the Accel and the truck fired right up. Turned the truck off, swapped coils, bolted in the OEM coil including an attached cable guide for some loom and a random ground wire but again, the truck wouldn't turn over. I removed the random ground wire from the ignition coil mounting bolts and the truck fired right up. While the truck was running I reattached the ground wire and nothing happened. I turned the truck off and then back on and it started fine. The next morning I was leaving for work and again the truck wouldn't start with the ground wire attached so at this point I think the ground wire is messing something up. It's relatively large gauge and goes immediately into a wire loom so I'm hoping to not tear the loom apart to track this thing down. Does anyone know what that wire grounds out? Thanks

Wanted to close this out to help anyone else. TL;DR: It was the soft line going to passenger rear brake and caliper were upside down. The whole story: The truck was pushing fluid just fine at the distribution block so I hooked up the hard line and disconnected the other end where it T's to the left and right rear brakes, still good flow. I continued doing that all the way to the soft line between passenger rear caliper and the hard line that runs along the rear axle. The soft line would only drip a little fluid so it was clogged. I had blown the hose out with compressed air and brake cleaner a couple times and seemed clear but when trying to push brake fluid through the system it was a no-go. So I swapped it out and started bleeding the system. Still no-go, exact same issue. Then I was looking at the brakes and noticed the calipers were upside down. I honestly don't remember taking them off at the same time but I'm an idiot so this actually makes sense. Swapped the calipers to the proper side and bled the brakes like normal.

DAAAAANG!!! This thing is SICK! I thought my Wildernest was the best camper for these old trucks but this is the pinnacle!

Reviving an old thread. I broke down and took the truck to a local Jeep garage and they don't have a definitive answer for me either. I'm going to bring the truck home and keep working on it because evidently the experts aren't much more help. I'll keep everyone posted. Pike: The rear disc brakes are original to the 8.8 that I swapped in. While rebuilding the calipers I did them one at a time so as not to mount them incorrectly.

I haven’t inspected the flow from the MC, just routes the lines back into the reservoir to bench bleed. I’ll grab a clear bottle and inspect.

^ this. Get some uv dye in the system and find the leak. Probably just an o ring which you should replace all of anyways, clean system well, add oil and reload. It’s shockingly easy to convert to r-134

I agree. I regeared my front 30 and rebuilt my rear 8.8. Both ring gears just slid on without heat

Pedal is soft anytime I hook up rear brake line. When I have the rear lines plugged and it’s just the front, pedal feels nice and firm.

No, rear valve is long gone

MJeff, the shuttle valve did trip a couple times and each time I reset it. The main reason I bypassed the dist block was to avoid any issues with the shuttle valve. Eagle, originally I plugged the bottom front. It worked great like that for years. Now I have all the front holes plugged and line from MC goes directly to rear break hard line.

I’ve replaced the BB and MC as well as rebuilt both rear calipers and blew out the lines while I had everything apart, there shouldn’t be anything in there anymore but if I’m not missing any major steps to bleeding then it must be something mechanical like that.

One of the key issues I’m having is that I’ll star bleeding rear passenger brake and it will move some fluid through, I’ll top off reservoir and then no more fluid will go into the system. I can pump the pedal 50 times with no change in fluid level in the MC. What would be causing this to happen? I thought it was the fail safe in the distribution block which is why I bypassed it but even with a direct connection from MC to rear brake line, the same thing is happening.

Pete, Master Cylinder has been bench bled twice (while installed though if that matters). No air left in it. Limey, Starting at passenger rear brake every time. No difference. Pizza, I did a gravity bleed. It took a long time because I ran a lot of fluid through each brake to make sure the entire line was flushed but as soon as I closed everything up my pedal was still super soft.

Hey everyone. ‘92 w/ 8.8 (disc), ZJ BB/MC and rear prop valve delete. My rear driver side shock nut worked itself off during an off-roading excursion and then my shock worked itself off the post, jammed up into the wheel well pinching my rear brake line and eventually wore a hole in it. I pulled the old brake lines and ran a new hardline but now my rear brakes won’t bleed. Ive used a one-person bleeder and hand pump vacuum bleeder no go. I plugged and bypassed the distribution block under the hood going straight from the MC to the rear brakes and still nothing. What am I missing or doing wrong? I’ve done lots of brakes and had to totally redo the system when I swapped the 8.8 so I know I got it right before.

It was a 120A for a v8 zj. Had to grind the brackets a little but nothing too serious.

So I got everything figured out. The "upgraded" alternator that I put in was bad and causing a short in the system (I think). One of times the truck started and ran I put the multimeter on the PDC and once the truck died, the voltage started dropping down to ~8V. The battery is new and didn't show any physical signs of being bad, all the new cables were properly grounded, all fuses were good, I had good fuel pressure at the rail and good spark but only sometimes. So it was an intermittent spark problem. I replaced CrankPS, ThrottlePS and CamPS along with new distributor, cap, rotor, plugs, plug wires and coil. My neighbor (a mechanic) mentioned he had a customer with a similar problem once they installed a high output boat alternator that "everyone on the forums" said would work but didn't and caused a bunch of other problems. So I swapped out my old alt and it's been 100% since then.

I replaced the crank pos sensor this evening and am charging the battery to make sure I get good signal. I'll let you know what happens in the AM.

Isn’t the camshaft position sensor part of the distributor though? I was under the impression it tells the distributor when to send signal in HO engines.

Update: I was able to get a little help from a neighbor today and really check over the things I've been trying to do solo. While cranking the engine I sprayed some starting fluid in the intake and nothing happened. Good news, it's probably ignition related. Next, I hooked up a spark plug to wire connecting ignition coil and distributor cap, grounded it on block and had neighbor crank. Sparked like crazy, nice and blue. Put wire back on distributor cap, put cylinder 4 spark plug wire on spark plug, grounded on block and had neighbor crank. Nothing. When I checked ignition before I was grounding spark plug on block and recording it w/ my phone while I cranked because I don't have anyone around to help me. I would see some spark but it must have been very weak and that would explain why the truck will randomly run and then die, it's getting spark every so often but not consistently. I replaced the distributor cap and rotor a few days ago hoping that would fix the issue but it didn't. I even put the old distributor & rotor back on to see if the new one was bad, still no change. Now I'm assuming the new cap and rotor are both good but that leads me to think it's the camshaft position sensor not sending the power from coil to distributor. Is that what CamPS does? Still no CEL and no codes.

Definitely have spark still. Fuel pressure peaks at 42 with pump on, 38 with pump off but doesn’t drop. Fuel pressure with engine on is steady at 30-32 with no bouncing and fuel pressure goes up as engine stumbles and dies. The fuel pressure going up as it dies sounds to me like an injector or valve issue, am I way off base with that guess?

So here’s when I’m at. I replaced the ignition coil, rotor, cap and spark plug wires as well as the fuel pump, strainer and fuel filter. I also replaced the coolant temp sensor because it was giving me a CEL. While working on the truck I left the throttle position sensor off and got another CEL which didn’t go away upon plugging it back in so I replaced that as well. Once that was all done, I hooked up the fuel pressure gauge, purged all the air out of the fuel system and it started right up. It idled great and felt strong when I would rev it a bit. I was elated. Today I decided to take it out in the road and try it out. I started heading out for a park uphill from my house in case anything happened and I’m glad I did. After maybe 1/2 mile of (pretty steep uphill) travel the truck started to miss and when I gave it more gas it died altogether. I put it in neutral and coasted back home, or at least pretty close. Now it won’t start again, no CEL’s. Sometimes it will start but immediately die and then won’t fire again. When it was idling well I pulled the CPS plug, it died, gave me a CEL, I plugged it back in, pulled battery cable for 15ish min to reset all codes and it fired up no problem so I don’t think it’s the CPS. Any other tips?

I have new plugs & plug wires coming to go with new ignition stuff. I’ll check gap on new plugs. Still needing to find the plastic adapter to make new fuel pump fit in assembly though