Finn

I have played with this thing all day and still the same problem! Instead of going the timing light route, I have been turning the motor to TDC and then playing with the distributor. When pointing at #1, (which is where it was) - same problem. I have tried installing the distributor on either side of #1 and it's worse. However I am not sure if I'm only moving the distributor one tooth at a time. How much movement in the rotor between teeth once seated? 4 to 5 o'clock or less? I've even tried another distributor out of the parts truck. :fs1:

I had my suspicions about timing, but because of my total lack of any experience I had to go the trial and error route. Had no idea the truck could idle fine with the distributor installed incorrectly. The other parts needed to be replaced regardless, so it wasn't a waste. Haven't played with a timing light before, but I'll borrow one and am sure Mr. Google will help me out there. Thanks a ton and I'll keep you posted. :clapping:

Firstly, I've been watching these pages for a number of months and this topic has been touched on but I still haven't figured it out. Thought I'd start with a new post with all the info. 1989 4.0 4X4. Motor is from a Cherokee (same year). I did not do the swap, but the problem has been present from that time. Truck starts and idles fine, but stumbles and backfires under acceleration so bad that it barely moves the truck. Here's what I've done so far; -Started with fuel filter. Plugged! -Inspected tank. Terrible. Bought new one from RockAuto and installed with clean, working pump/hanger from a running parts truck. -Blew out fuel rail and supply/return lines. -Installed new fuel injectors. -New quick connect fuel line couplers. -Replaced fuel pressure regulator from the same running parts truck. -New EGR valve, used EGR solenoid from parts truck. -New oxygen sensor. -New front and rear vacuum harness from RockAuto. -New PCV valve/crankcase vent hose. So with all that I'm thinking it's not the fuel or vacuum. Dristributor cap is not fouled but it almost seems like the timing is not advancing under acceleration. As stated, this is a 4.0L from a same year Cherokee. Under my inexperienced inspection all electrical seems to be connected. I've just about wore the pages of my Haynes manual out trying to find the problem. I became a member on this site when I got the truck late last fall, and really admire the knowledge packed through these pages. I'm hoping someone can point me in the right direction. Thanks in advance,,,, :dunno:

The mechanical sending unit on the gauge cluster I bought won't work regardless of what adapter I use - its too big. Is there another place on the block I can use for temperature? The passenger side of the block is easily accessible, but nothing is jumping out at me. Driver's side of course is mostly hidden by the intake/exhaust manifold. Otherwise, do I have to go with an electric sending unit? :mad:

Thanks, I'll give that a try and confirm if it works.

Anyone know the thread size of the temperature sending unit offhand? (89 4.0L). I need an adaptor for the aftermarket gauge set I bought,,,, :dunno:

I've just been through the headache of a tank swap due to corrosion, and the old sending unit was a goner. Got another out of a parts truck - I would definitely buy one to have as a spare. :Canadaflag:

I notice Ox now offers an electric shifter. Anyone have any experience? Pros/cons?

So is this place improperly advertising this as a Comanche unit? :dunno:

It looks like someone is manufacturing fuel sending units for the Comanche. Anyone know the details, or is this a generic one manufactured for the Cherokee? Picture looks just like the one out of my 89,,,, http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=160540362869&ru=http%3A%2F%2Fmotors.shop.ebay.com%3A80%2F__%3F_from%3DR40%26_trksid%3Dp3841.m39.l1313%26_nkw%3D160540362869%26_sacat%3D%26_fvi%3D1&_rdc=1

I'm in the process of a tank swap for my 89 Pioneer short box. 18 gallon tank from RockAuto (JP5B) is a direct replacement and existing setup has 2 straps with the skid plates attached to bottom. :wrench: Maybe I should start a new thread, but the reason for the swap was extreme rust inside and out from sitting. In the process the sending unit was damaged while trying to clean it. I was able to get another off a recent parts truck purchase but I was sure I found a complete NEW pump/hanger/sending unit that will work and advertised as a replacement for the Comanche (not Cherokee). I think it was manufactured by Airtex, but can't find it anywhere online now. Has anyone seen this/bought one? Thanks.

What year are those Cherokee doors? Were they a direct swap?

I don't know of anyone else that makes them. Have you scrounged around at all of the junkyards yet? Some people have made other small pickup (S-10 & Ranger) bumpers work in a pinch. I may have to get a factory original from a junkyard for now just to pass inspection - I was just hoping I could get a well built aftermarket right off the hop. I emailed JC Offroad about their rear MJ bumpers - just to see if there was any chance of bringing them back into production. No bites, just a reply saying they discontinued due to lack of sales. Looking forward to seeing some plans. I may just have one built here and along with a few other issues rectified I can pass inspection and have her on the road by spring,,,,,, :clapping:

New MJ owner, and new to the forum. I need a rear bumper before I can get my 89 registered and on the road as it needs a safety inspection (rule when newly registering in this province - the beast came from BC :Canadaflag: ) Very interested - especially when I noticed that JC Offroad is no longer offering the rear bumpers. Just hope the shipping doesn't kill it,,,, Is no one else manufacturing rear bumpers????