Green Mesa XJ

If it’s a manual transmission I’d go ax-5 with np231, they are plentiful and usually cheap. Ax15 is the gold standard because it’s so tough, like the Toyota versions (r154) it’s sought after by people doing upgrades. There was one year the Cherokee /mj got the aw4 transmission for the 2.5, aw4 too is a legendary transmission. I forgot about the t4 & t5 in the Hollander break down there is a choice two manual transmissions listed. Sent from my iPhone using Tapatalk Pro

Some led headlights are cheap knock offs, they sell anti flicker harnesses to help eliminate these kinds of problems. I'm planning of getting some led lights for our jeeps so I’ve been reading reviews, One review said it’s a H4 anti flicker harness these jeeps need. Far as the radio, that makes no sense unless the wired it or the headlight switch wrong. Btw these headlight switches can melt, a lot of us have added additional headlight harness to take the load off the factory wiring. I’m not sure if you use harness kits if you’ll need Ed anti flicker Sent from my iPhone using Tapatalk Pro

Is the motor locked up? Can you turn with a hand tool at the bolt for the crank shaft pulley? Sent from my iPhone using Tapatalk Pro

I’ve used spectra rad in on of our cars with no issues. When I replaced the jeeps radiators I went with metal tank, last one was a two or three row for the 4.0 HO Jeep. No other reason than I don’t like plastic tanks on the radiators. In the last two years all the radiators I’ve replaced were inexpensive welded aluminum radiators. Decent quality and the were so cheap compared to what I paid for off the shelf stuff at Vatozone From what I’ve noticed Spectra is usually look very close to factory specs and are the same quality or better local parts houses sell for more. The spectra rad I put in was a car with a turbo engine, it was nearly identical to the factory rad and it cools well, especially considering it’s the heat of the south and a turbo adding to the engine heat. Sent from my iPhone using Tapatalk Pro

Is the engine harness original off the 2.8 Jeep ? Are you using all the factory Jeep/gm ignition off the 2.8 engine? I don’t know what the 3.4 has for ignition coil If it’s all factory Jeep then the tach should be correctly wired. Either bad cluster tach or something was cut and spliced on the engine side Sent from my iPhone using Tapatalk Pro

I was assuming the Jeep was using the factory 2.8 harness, if it’s using the 3.4 or electrics from it I’m not sure how it’d work Sent from my iPhone using Tapatalk Pro

Those instruments are simple, the tach wiring exists in the harness regardless of trim package options. Unless someone cut or altered wires going to the ignition coil it’s working up to the point it goes to the gauge. Do any of the gauges work? There is a fuse that powers the gauges. These tachometers are easy and simple, if I remember I’ll break out the 86 electrical trouble shoot guid a post a few pics. Although I might have already done that responding to posts here years ago, Looking back at my orders I bought a cheap tach from amazon to test the dash against Docooler Tachometer Tach Gauge with Holder Cup for Auto Car 2" 52mm 0~8000RPM Blue LED Light. I see some have given it poor reviews since then. Might be better ones out there. I used it only to test the other gauge clusters, didn’t install it for daily driving. Sent from my iPhone using Tapatalk Pro

Just catching up on the recent posts. Maybe the O2 sensor will fix it, they can cause all kinds of problems. The check light for a O2 failure on the 91-92(?) were a separate light from the check engine, that required a Chrysler/jeep tool to reset, many owners just pulled the bulb. I have two PCMs from when I was testing the pcm by swapping, on the original pcm the O2 light been reset by Jeep, the used PCM had the light come on. I think it was mostly a mileage thing or perhaps when it failed the light stayed on, i don’t remember correct the answer now. My random thought is if this Jeep still a random problem try swapping in a different PCM, they don’t often fail but when they do all kinds of crazy problems can intermittently appear. The odd problem we had I think was water from the windshield leaking got the brake switch and/or TCU and caused the situation where my in-laws thought they jeep didn’t have power on a hill, couldn’t accelerate, etc, I never saw it and most of that they describe about vehicles having trouble is normally wrong. On the fly I replaced the TPS and Brake switch, on the 91 up the brake switch surprising ties in to a number of systems like Cruise control and the torque converter locking up or not. Similarly TPS also ties in to a few systems. And tps could cause issues with power. I was never sure about what the problems was, I had to drive a ways to pick the Jeep up from the house where they left it parked, so I picked the parts up and took a chance on fixing it and driving back. Never gave me any trouble, been years and lot of miles and a few 3 hour trips on the highway since then. Of other odd problems those 91-up 4.0 Jeeps have is crank position and cam position sensors, crank position on the bell housing is famous for the woes it causes. Cam position is not as infamous but can cause all kinds of trouble, some times it’s actually the distributor physically wearing out wobbling around. On the 1991 4.0 the cam position sensor was a pain, I think it had to be removed by taking the distributor out and taking it apart, many years since I’ve messed with it so I might be wrong. But I do remember it was easier to replace it with a rebuilt, I pretty sure the later 94-95 distributors could be swapped in as the signal was the same and so were the plugs on the harness. The benefit being the cam position sensor was easier to replace. Sorry to ramble on randomly, maybe this helps somebody. Edit: I forgot about the MAP sensor, never actually had one fail on those jeeps. But if the vacuum line becomes disconnected it runs poorly. Sent from my iPhone using Tapatalk Pro

No that’s a ashtray or footwell light. I thought you only had to use two of the wires and a resistor to make it work. Sent from my iPhone using Tapatalk Pro

There is a hidden ground in the panel somewhere behind where the spare tire sits I’ve had my fights with these senders, kind of wised I left it alone. These gauges are wonky on a good day. don’t think ethanol did these electronics any favors. The floats and the sender just seem send erroneous signals. Ive swapped out gauges trying to find the problem , actually the original gauge cluster has a peeling printed circuit, so did the early 1987 cluster I put in. Later 87-88-89 cluster seem to have better printed circuits. Checked grounds, added new grounds, cleaned plugs and circuit plugs on the cluster side. Eventually I put a new 1986 sender in the xj because 84-85 senders were not available, plugs were different so I got the proper pig tail and rewired most of the wiring for the fuel sender. basically the original sender was the really bad part of the equation. Gauge levels still likes to move around a little but no where as bad as it was. It was a lot of work and trouble shooting to end up pretty close to where I started. Sent from my iPhone using Tapatalk Pro

Probably not wired correctly. Be good to bench test it anyway to be sure. I’ve seen the two wire plugs fail, only charge when the wires or plug were moved. My guess is the plug or jumper you built isn’t quite right yet. I’d order one of those kits mentioned earlier just to have it simplified. At one point it was a bigger pain to convert from the old alternators to the newer style seems like enough people wanted to upgrade they made kits to make it easier. Sent from my iPhone using Tapatalk Pro

I do have a pressure regulator set up, plenty don’t bother. If your electric pump is in spec it’s not a big deal. I ran for years without a regulator only added one when I changed out the old Weber for a new one because of erratic idle (probably a clogged jet). Could have rebuilt it instead but didn’t have the time. When I swapped it out I added the regulator to be sure the fuel pressure was right on the money. Sent from my iPhone using Tapatalk Pro

I pick one up from advanced auto a few years ago to test how accurate the jeeps tach was, picked up a couple 89 clusters and wanted the best tach of the bunch, I’ll try to find out which one I got. Amazon would be another good choice. I couldn’t get the video to load in my phone, may try the laptop in the morning. You using the original alternator or the 3.4 ? Sent from my iPhone using Tapatalk Pro

What Eagle said. When I learned this stuff it was the sound of the engine that I would pay attention to, but then I knew the car and I suppose how it was supposed to sound. Any pinging or flat spots driving I’d go back and start over. Actually had to do all of this basic stuff last summer, we picked up a old Toyota sports car the original owner and his buddy put a new engine in it, then the car sat for 13 years as the guy was working over seas. They had it all kinds of jacked up, so bad we couldn’t time the engine because bad knock sensors , vacuum lines and other things were completely screwed up. I had to set the timing completely by feel to begin to get a starting point. The fact the car even idled when I got it was a minor miracle, cause it shouldn’t have with the timing as far off as it was. The estate paid some run of the mill mechanic to get it running but he couldn’t figure out how to get it driving. That’s just sad that someone doing this for a profession, taking people’s money to fix this car was out of their depth when a code reader couldn’t tell them what to do. I know original owner loved this car his dream was to retire, restore it and go driving. But what they did trying to fix it was worse than leaving the old engine in even with it burning oil. It was kind of like car archaeology, once we worked out enough of the errors to get the rpm right and the computer error free long enough we could set the timing properly, turned out It Wasn’t that far off with our seat of the pants trial and error. One old test use to be starting off in second, if the car didn’t sputter or bog down it was tuned properly. Could just be an old mechanics tale. Is you mj drivable? Sent from my iPhone using Tapatalk Pro

Not sure if it’s still sold when I first got my 2.8 xj it didn’t have a tach so I borrowed a old fiends mechanics tach and hooked it up to do the first tune up. I suppose you could buy a aftermarket tachometer and wire it up to get the rpm reading, it fairly straight forward. Modern cars don’t really need the old school tune up tools because the pcm has a readout for all the necessary data. How does it sound? Sent from my iPhone using Tapatalk Pro

How the hell are you supposed to time those engines with the Vara-Jet E2SE ? Just disconnect the plug at the distributor? Looking at my Haynes manual it covers the vacuum advance but not the electronic distributor. Sent from my iPhone using Tapatalk Pro

Looks like you won’t need this I’ve never seen that dial on the timing gun before. Too cool. Is you water pump Turing the correct rotation? , I remember gm switched between clockwise and counter clockwise. Or vice versa. I think you had it correct for the rotation for the 3.4 but your belt was routed different from the stock 3.4 The other thing you need to know if how to trip the cpu for timing the 2.8. The federal emission Vacuum advance is simple, disconnect the vacuum line and temporary plug it. I want to say the 2.8 with that distributor you connect something to a plug in the engine bay sending in to a timing loop. At least that’s the way a lot of 1980s car and early obd ecu did it Sent from my iPhone using Tapatalk Pro

Um, the Weber choke is supposed to get power when the ignition is on, otherwise it’s a power drain and always on when the Jeep is parked When running it gradually opens the choke as the engine warms. Looks like I powered mine from the plug that used to go to the warming element that was under the carb, junk, got rid of it long ago, I bought a gm pigtail plug to use the plug instead of splice into to bring power to the electric choke. You should have one big vacuum line and one small line the Weber requires, should be easy to match up as the old carb had used the same lines. Getting rid of the factory carb means you don’t need most of the vacuum lines under the hood. This it the idle screw I remember you had over heating trouble before. Hope that’s fixed. Far as the cpu the adjusts the timing instead of vacuum advance find the factory instructions for timing those engines either Jeep or whatever gm had for those 2.8 carbureted. Sent from my iPhone using Tapatalk Pro

http://www.redlineweber.com/html/Tech/38_dgas_tunning.htm Try this link. Powering the choke was a matter of tying in to something that only powers up with the key on run. I’m not sure what your wiring look likes but there should be one or two sources near the carb that only become hot (powered) while the engine is on run. As fir keeping that distributor I dunno. It ties back to a computer, somewhere, even as limited as it is, it controls a lot of how that engine runs. I know nothing about that set up, I’m sure there’s a write up somewhere of somebody putting Weber on a California Mission S10 or jeep Sent from my iPhone using Tapatalk Pro

The Weber is simple to tune. Right now i would leave the fuel mixture alone, should be set from factory more or less where you’ll need it. I’d leave it alone unless it has to be adjusted. The last Weber I bought I just threw on, reconnected it and set the idle. After the cold idle releases, you can set the warm idle. I’m kind of assuming idle was bumped up to keep the engine running, but if not double check the basics. Make sure you don’t have any vacuum leaks or leaks at the base where the carb mounts, then it’s a matter of adjusting the idle down. On the side of the carb where the linkage is for the throttle, there is a screw that can be adjusted up or down to set the warm idle, maybe some call it curb idle. The screws at the center front and back are for the mixture, at this point I’d leave them alone unless they’ve been adjusted way out of spec already. Not hard to retune them just unnecessary at this point. Here is a link for the Weber instructions http://www.redlineweber.com/html/Tech/38_dgas_tunning.htm First thing I do is set tdc and find zero. Then I’d double check the carb is set up right, no leaks, correct vacuum lines, good fuel pressure, and wired up correctly not that you’ll need much wiring. Should be all in the instructions the kit came with. Far as timing without markings I have no idea, but I’d follow what eagle said. Did you ever get the federal emission distributor set up? As I remember it your MJ had California emissions. Sent from my iPhone using Tapatalk Pro

Yes it’s a 2.8 timing cover I don’t have a frame of reference, the 3.4 has a different water pump , if I had to guess I’d say between the two bolts( in the last picture of the cover and crank pulley) for the water pump, closer to the left side (bolt nearest your right hand) , that’s if they are anywhere near the same bolt location . If you look at the 2.8 pictures you can make out where 10 btc is by counting the notches. That’s where 10btc is going to be regardless of the timing cover, mechanically that’s where it should be on those engines, I’d look for bolts or something similar on both covers to make a guess on where it is in the 3.4 cover. Bigger question is does the 3.4 crank have markings for timing the engine and did you ever set tdc? If you set zero you should be able to make slight adjustments to get it close enough. Sent from my iPhone using Tapatalk Pro

Honestly I don’t know 2.8 vs 3.4 pulley, ought to be similar. , timing mark it’s on the top left side, right hand standing in front, below the water pump About where the 3.4 should have mounting points for its crank sensor, if that’s what that sensor is. Sent from my iPhone using Tapatalk Pro

Well I found them. Hope this helps Sent from my iPhone using Tapatalk Pro

Bud, I believe I posted the best pics I could at the time of what the 2.8 timing cover and markings looked like. Search some of your old threads I’m sure it’ll be there. Original timing would be something like 10 degrees btc. With vacuum disconnected at idle, (700 rpm? ) don’t have those pictures on my phone or I’d repost them. No idea how to guess set without those marks, best guess would be make a mark on the 3.4 cover based on where the 2.8 marking are, then fine tune by driving it. But this is a little out there for internet mechanic online stuff. Hands on I’m sure I could set it, or get it close enough. Telling somebody how to do it is another matter. Sent from my iPhone using Tapatalk Pro

Oh, some useless information about the 2.8 86 MJs have a mixed bag, in 1985 gm upgraded the heads, rear main oil seal, and crank, Heads were used 1985-1995 , same head as a 3.4 Oil seal is a one piece rubber later gm motors got. Crank has bigger oil journals and main bearings , I believe these main bearings are used until the end run of this block. Could be wrong. These later 1985 block 2.8 could be rebuilt with newer parts, I want to say a 3.1 is just a stroked out 2.8 and the guts of the 3.1 engine can be swapped in to the later 2.8 block. It’ll have the same differences a 3.4 would, like internal vs external balancing. But if you’re going that far just put a 3.4 or something better in. Here’s the catch for 1986 2.8 XJ and MJ owners, the later block would be more desirable, if any 2.8 could be considered that, but gm supplied their cars and truck first with the newest blocks and heads, so Isuzu and jeep got the left over 2.8 gm didn’t want to put in their vehicles. 1984 Jeep models got 1982-83 gm engines, 1985 models got 1983-84 and 1986 jeeps got a mixed bag of some getting 1985 improved engines. But all this being said unless you’ve got to have a mechanical fuel pump, pull the original 2.8 out and don’t look back. Sent from my iPhone using Tapatalk Pro