ParadiseMJ

You may want to look at your catalytic converter. Listen for a rattle, see if glows at night. New cat ~$125-$175 installed Backfiring can definitely relate to timing, but you haven't mentioned the cat being clogged, or falling apart. Exhaust back pressure can cause backfiring too, and would flatten the hell out of performance. So, just an idea that I hadn't seen

Makes more sense to me too, thanks!!

...simple enough, I hadn't thought it out.

I'm looking at a couple of other Jeeps for donors to my 88 MJ...a couple questions. #1 donor - 88 MJ with a munched front right, not real bad, needs hood, fender, header panel, lights. the rest of the body is straight, nice and clean as is the interior. 4.0L, Column shift (which trans is that), 2 wheel drive, D35 (did not check the gearing). $300 #2 donor - 90 XJ, 4.0L, AX15, 8.25"/D30 w/4.10's, NP231. The body and interior are toast (dents, rips, stinks, redneck electrics) The patient - 88 MJ 4.0L, BA-10, D44/D30 w/3.07's, marginal electrics (fuse box is iffy). $450, no rust, but needs paint, interior is naked, stripped, wires hanging from the PO. What I want is MY MJ with the better trans and gearing and an extra 4.0 laying around to possibly stroke down the road, but I'm also concerned with body work, paint, and the %^#$$% wiring. I await guidance. :bowdown: I can't afford to buy BOTH Jeeps (not including the divorce that would surely follow)

CAT, as in CATalytic converter. If it's clogged and/or toasted you'd get bad mpg, flat acceleration, poor performance. Simple test is to run engine up to temp (even at highway/city speed) AT NIGHT to see if the catalytic converter is glowing red. If so, and you've never changed it out (~~ $125-175 installed).

Did you actually PUT 23 gallons in it and run it until empty? Or are you just dividing 300 by 23? Even at that it comes to 13 mpg, not unheard of. Bad, but not crazy bad. Miles driven divided by fuel used instead of the size of the tank...that, and what size tires you're running vs. what was stock (speedo/odo calibration). If it still turns out that you're getting 13 mpg. I'd check the 02 sensor, condition of ignition parts, cat, coolant temp sensor, vacuum lines etc. to get a finger on why you're running so rich.

I thought my XJ didn't have any dash lighting (other than the instrument panel) but the little icons on the black dash panel do all have lighting behind them. That's what that plug looks like. If the little icon for the lighter doesn't light (other than the blue ring) that's a light socket. I think it's a 194 bulb, and there should be a hole for it to go in to.

Take the t-stat out. Drill on the flange, the round part that surrounds the meat of the stat, think of it as the ring around Saturn (the planet, not the car). Drill anywhere EXCEPT close to either edge. Install t-stat with the hole at 12 o'clock position (not the time). Also get yourself a new 16lb. radiator cap without the lever. On a closed Renix system you can drill a hole at 12 and 6 o'clock.

You were right about the additional grounds at the dipstick. When I pulled that stud at the dipstick I thought it was strange that there were 2 washers on it. Well, they weren't washers, they were ring connectors that had rusted/broken/corroded off. :doh: I put a couple of crimp on 5/16" connecters on the 2 sets of 2 wires each. Polished up the stud and the block. The FP sprang to life, just like it should, on for appx. 3 secs and stopped. Got a good sqirt from the schrader valve on the fuel rail. :clapping: I'll put a gauge on there when I get one (payday tomorrow) Still no spark though, so, I'll be doing the CPS (CKS)...wait for it...NEXT YEAR!! Thanks for the help and suggestions. ***as far as the black widows, there are only 2 things that worry me around here...black widows and skunks.

You shouldn't have to. It's an open system, meaning open to atmosphere. Coolant is added through the coolant overflow bottle. In a perfect world, when the coolant heats up, it expands and moves into the overflow (along with air bubbles). When it cools it should suck coolant back in to the radiator (without air bubbles). It should be self "burping". If your overflow runs empty it will suck air but filling it back up usually remedies that in a few cycles. Just to be sure you can a.) buy an OEM t-stat with the little toggle hole in it or b.) drill a 1/8" hole in the t-stat flange (inside). Check the level of the coolant overflow when cold and then again when hot, should be a difference

The FP ground looks as if it comes right out of the bundle. Looks stock!!? The Black Widow webs all up in there have me a little worried, :eek: I'll have to spray for bugs and go back in there when it stops pouring. I'll put the new CPS in there and see if it clears up my probs.

I have searched this but didn't find the answer yet. I read up on chassis grounds since the PO had the bed off before I bought the MJ. I looked in the tail light bucket and found the ground in there less than OK so I shined everything up and tightened THAT ground up. Then by the fuel pump there is another ground (looks like ~12 ga. wire) to the frame rail. Is there supposed to be another ground from the cab to the bed? Bed to the frame rail? I'm trying to chase down the fuel delivery issue. I have NOT changed out the CPS. The FP relay is clicking away. I swapped it with a good relay from my XJ. Still no joy. I have replaced the block to firewall strap with a 4 ga. cable, and an additional ground from neg post on battery to body. Headlights, tail lights, markers all work. Front blinkers, parking lights do not work.

Some is already changed out (new) as is the filter. I'm wondering if the fact that the tank is open to the air is causing part of my problem.

So, I think the deal is that the filler hose has to be sold with the return hose. I believe the "return to tank" line is 5/8". I think I have the brain power to engineer that. I have to look again at the filler itself, the metal part. The PO had removed the bed and the hose(s) just fell apart in his hand when he dropped the tank. ...and now I'm hijacking my own thread... ...is it possible that since the filler hose and return line are presently disconnected that I would have a fuel delivery problem. The thing won't start. I installed the new ICM and coil that came with it, but the fuel pressure seems low ( haven't put a gauge to it yet). With the key on, engine off, it just piddles. I have had it started but now it just cranks and cranks, and doesn't start.

In an emergency I've had to pee on my door lock. Worked like a charm. ...but if I had to lock them up in consistenly freezing weather I'd go the graphite route.

:cheers:

:doh: Duhh, yeah but I already gave my Aunty her Christmas present. She hasn't been out of her room since yesterday. :yes: I was just looking for some information before I drop the tank and put it all back together. Part my project is getting the whole system back to specs. :smart: Thanks for "ur" help.

I have to agree with you. The NAPA store here said they "couldn't find it". I'll have to try the NAPA down the hill. It's the one I found at carparts.com that says "unlawful in CA". It has something to do with the smog police pressure testing. So, I'm thinking there's gotta be another P/N.

I bought this MJ (88) and the guy told me it needed a fuel filler tube (pipe, whatever) so I looked it up on carparts.com. They have it right there, BUT, it says it is not legal for sale or use in CA. Does anyone have any info on this? It just looks like a rubber hose (says it's safe for fuel, alchohol, etc. What part should I be using? Nowhere to be found on Autozone or O'Reilly's web site.

If you have a closed system with the pressure bottle you need the metal (90 and below)plumbing and vac actuated directional heater valve. After 91 the heater valve is completely different. I converted my XJ to an open system and I run the hoses straight to the core and back, no heater valve at all. Better flow, 4 less hose clamps, nice heat, cold A/C. Closed system still requires all that plumbing.

My XJ (90) has a football...My MJ (88) has a grapefruit... The only difference between the two Jeeps is that the XJ has cruise control, the MJ does not. My understanding is that the football has 2 chambers (one for HVAC, one for Cruise) and the wall between them is solid. So basically the football is just a way to have 2 chambers without having 2 grapefruits. A uni-boob if you will.

Undergeared. So, if I have a D30 front in 4.11 LSD (yard) available I could have a shop re-gear the D44 to 4.11 (local honest guys, I know) for about $__________ (fill in blank). P.S. I have 3.55's on my XJ and a step up to 4:11 seems cheaper if I nab the D30 4.11 for $100. :dunno:

...I now see :bowdown:

I would likely swap in a non vac 30 in front. So far I have a whopping $550 into this Jeep which includes a trip to the boneyard for a header panel, tailgate, bedliner, mirrors and various other engine and vacuum system parts. Since I'm doing all the work (except re-gearing) I'm hoping to do the whole thing for whatever I sell the XJ (with 230K miles on it) for. Only 169K orig. miles on the MJ.

Thank you, that makes it all alot clearer. Looks like a big part of the restoration is re-gearing.