89 Comanche - Rex

[Rex89]

Got this 1989 MJ SporTruck back in April 2025 and am finally getting around to starting a thread! I've done a lot to it in the last few months, mostly fixing things. But I have lots of plans for it!

 

It's a short bed with the 4.0 and is 2wd with the BA10. I'll swap in an AX15 and convert to 4wd eventually.

 

The truck's build date is February 28, 1989, just a few weeks after I was born! I'm from New Orleans and my mom told me that if I had been born on Mardi Gras day, she would've nicknamed me Rex. So even though this truck wasn't "born" on Mardi Gras, I decided to give it the nickname I almost had!

 

This is how it looked a few days after I got it:

 

 

 

 

The story of this truck actually kind of starts way back in 2017 when I was gifted a 1973 Chevy K5 Blazer from my grandpa. It had a 350 sbc and the SM465 with granny low gear. The original owner was my grandpa's neighbor, who had been a Navy welder in WW2. He custom made the front and rear bumpers (see below photos).

 

My grandpa never actually drove the Blazer, it just sat in his yard until he gave it to me. Over the years, I never really got to do much to it other than adding a rear seat, getting new tires, and cleaning up some of the rust. It was mostly just parked at my in-laws' house as I lived somewhere without space for it.

 

 

 

 

 

 

I've always had a thing for smaller compact pickups. My first truck was a 98 Ranger. I also remember fondly my grandpa taking me fishing in his 91 S10 when I was a kid. The Blazer was my first "project" truck and it was great, but it was a little big for my tastes.

 

When I first got the Blazer, I began to research other old trucks and I soon learned that Jeep had made a compact pickup in the late 80s and early 90s! That began my obsession with the Comanche.

 

Due to various job changes and other life circumstances, it was never in the cards for me to get a Comanche until this year. The deal was that I had to sell the Blazer in order to fund the Comanche purchase. That was a tough decision because of the nostalgia factor. But I ultimately decided that my grandpa would have wanted me to have the truck that I really wanted.

 

So I sold the Blazer to my father-in-law and I began to scour Facebook marketplace for a Comanche. I mainly just wanted one that was running and driving and that had the 4.0 and a standard transmission. I eventually found a good deal on one up in Huntsville, Alabama, so my father-in-law and I took his trailer the 7 hours to go pick it up!

 

 

 

 

 

The truck had spent its entire life in northern Alabama. I'm the third owner (I'm pretty sure). The previous owner only had it a few months and had put newer Wrangler wheels and bigger tires on it with a small lift. He had also added a new starter and a new fuel pump and filter (which I very shortly had to replace...  but that's a story for a future post... ). 

 

Since purchasing this MJ in April, I've bought 2 more Jeeps! A 99 TJ in June and then an 87 MJ in August. That's 1 Jeep every 2 months... and it's now October, which means I'm due for another one (although my wife disagrees)! I have been on the lookout for an XJ tho.... 

 

Eventually I'd like to add an AX15 and 4wd, I might go back to factory wheels, I'll get new paint and decals, add AC (very important for south Louisiana!), add a headliner, reupholster the bench seat, and plenty more. I have lots of work to do on it, but I really love this truck!

 

[JZLAJeep]

1 hour ago, Rex89 said:

Since purchasing this MJ in April, I've bought 2 more Jeeps! A 99 TJ in June and then an 87 MJ in August. That's 1 Jeep every 2 months... and it's now October, which means I'm due for another one (although my wife disagrees)! I have been on the lookout for an XJ tho.... 

 It happens! There are 5 Jeeps sitting outside my house currently and helping my neighbor find a XJ. When he decided to get an XJ for his son he came to our house for help. For some reason...

 

Oh, and nice looking pickup!

[olddude]

Good looking truck!

[Rex89]

Thank y'all!

 

So one of the first things I had to do was to get an air intake hose for the throttle body. The throttle body was completely uncovered and the previous owner said he couldn't find one that fit. I ended up ordering one on ebay, but I've found a few at junkyards since then that I'll probably sell to recoup the cost of the ebay one that I bought. But it gave me an opportunity to clean the throttle body out which it needed anyway.

 

 

 

 

 

Not long after that, I noticed something strange when I was inspecting underneath the motor... Someone had plugged up the tube underneath the charcoal canister... with a stick  

 

I couldn't find a picture of the stick still in the tube, but the first picture below is the tube I'm referencing. They had the stick shoved in the tube, pushed the tube/stick upwards, and the stick itself was just resting on the engine block. It was nice and charred.

 

 

 

So I figured I'd take the charcoal canister off, clean it up, and change the filter.

 

 

 

 

The old filter was pretty nasty...

 

 

There were also a couple of vacuum lines disconnected that I hooked back up. That all helped it to run a little smoother.

 

[Rex89]

Then the electrical fun began! The most pressing issue was that the taillight fuse kept blowing. As I tried to fix that, I discovered a lot of wiring issues. None of the below photos were causing the issue with the taillights though. I solved that a few weeks later, but I'll get to that in a future post... 

 

Below are just a few of the many things I found. Bare wires, loose crimps, etc.

 

 

 

 

Also I've heard varying opinions on using wire nuts like this for automotive applications, but I was always taught not to do it. There were quite a few of these in there.

 

 

The blower motor also wasn't working, so someone had wired up a little switch directly from the blower motor to the battery. Although I didn't solve the issue for a few weeks, I decided to remove this switch and associated wiring because it was kind of janky.

 

 

This is a portion of the wiring I cleaned out.

 

 

And here's a bonus photo of one of the many wood screws holding parts of the grill and light bezels on. I didn't fix all this for a few more weeks yet, but lurking behind these were plenty more wiring nightmares! 

 

[Rex89]

Not long after all that, I came close to blowing it up! I decided to take the Comanche for a drive on the interstate for the first time to see how it did.

 

Well it mostly did okay... except the high vibrations wiggled the hoses loose from the fuel filter. It was still running fine though because there was still fuel getting to the fuel rail. Why did the hoses wiggle loose though? Because the previous owner didn't put hose clamps on them... 

 

This is the only picture I took before I slapped some clamps on really quickly. It's a poor quality photo because I was in a panic as fuel was all over the ground.

 

 

When this happened, I was driving to my wife's work to drop something off. She came outside and said "hey why is your truck leaking?" I had noticed a potential coolant leak a few days prior so I didn't even get out of the truck to inspect it. I just told her, "Oh it's probably just a coolant leak, I'll look at it when I get home." 

 

So all the way home I was spraying fuel out all over the place. If I had just glanced out of the truck to see where she noticed it was leaking, I would've realized it most certainly was not coolant!

 

When I pulled in my driveway, I opened the truck door, and was met with what sounded like a garden hose spraying. I freaked out, shut the truck off, opened the hood, depressurized the fuel line at the schrader valve, but it was still leaking pretty good. So I put down one of these absorbent mats and slapped some clamps on in a hurry.

 

 

 

 

Turns out that not only were the fuel filter hoses not clamped, but the filter itself was just zip tied to the brake lines. That's partially on me for not inspecting all of that before it became an emergency. Despite all the wiring work I had been doing throughout the truck, I just completely missed these glaring problems. But luckily nothing exploded!

 

I also wasn't sure that the previous hoses that were on there were rated for fuel injection pressure. So I replaced those with the correct hoses and clamps. I also made the best makeshift bracket for the filter that I could with the materials that I had on hand at the time.

 

 

 

 

Although it was a scary situation, it was sort of a good thing because when I was depressurizing the system, I noticed a few of the injectors were also leaking.

 

 

I decided to go ahead and replace all the injectors while I had the fuel rail off. I don't think I have a picture of the new injectors when I first installed them. I also got a proper fuel filter bracket on ebay, but I couldn't find a photo of that either.

 

In the midst of all this, I noticed that one of the gas tank straps was bent. I still have yet to fix this... 

 

 

The previous owner also put a new fuel pump in, but I think it must be for an XJ or something. The lines aren't angled enough to avoid the hoses hitting the parking brake. I put new fuel injection hoses everywhere and they seem to be clearing it well enough though.