Eagle

After it has sat overnight, when you turn the key to the RUN position (not START), does the fuel pump run for a few seconds and then shut off?

Huh? ???

That's very possible, the the way to test that is a noid light. But the CPS controls both the ignition and the injection, so if there's a signal to fire the spark plugs, the problem isn't the CPS.

I don't know what Texas requires, but all XJs and MJs had catalytic converters. If you are doing a complete exhaust, I would install a cat. As to the best sound, IMHO the only aftermarket exhaust system for the Jeep I-6 engine that doesn't sound like crap is Gibson.

Slow down, and help us by giving enough information to diagnose. You may have more than one problem. First: the blower. Does the fan run? If the resistor pack is bad, it should still run at full speed with the control is moved to HIGH, because the resistors reduce the speed. High speed doesn't go through a resistor, so that should always work even with a blown resistor pack. If the blower runs on high, you need a resistor pack. If the blower doesn't work at all, go to the engine compartment side, unplug the connector to the fan, and try hot wiring it with a separate ground and a wire right from the battery. If it doesn't run at all, you need a blower motor. Not a surprise if that's the case -- the motors use brushes, and they do wear out. Second issue is where the air comes out. As noted, the controls are actuated by vacuum. Even a small vacuum leak can stop the heater controls from moving the flappers. The default is to send air to the top-of-dash defroster outlets. If you have a blower motor that works, and the air is coming out of the defroster outlets, you need to look for a vacuum leak. Third is that the Renix years (which includes the '88) have a vacuum controlled valve in the coolant line leading to the heater core. Make sure that valve is functioning (or just bypass it). Last is that the heater core is now 25 years old. It would not be a surprise if it's completely clogged, especially if it hasn't been maintained. You may be looking at a heater core replacement. If the dashboard is already open -- do it anyway, as a preemptive strike. When the heater core springs a leak, it dumps coolant into the passenger side footwell. It's not pleasant.

??? It starts when the key is in the START position, so the fuel pump must have a ground. The problem is that he's getting power to the fuel pump through the starting bypass circuit, but the fuel pump is NOT getting power when the key is in the RUN position. So how do we trouble-shoot that? For openers, although the ballast resistor has been replaced and then by-passed, I saw no mention of testing the circuit. You've got two nice, big, fat contacts there so I would begin by putting the key in the RUN position and check to see if you have 12-volts at the ballast resistor. (Actually, it'll be 12-volts on the upstream side, and something like 8 or 9 volts on the downstream side.) If you have power at the ballast resistor, then look at the wire from there to the fuel pump. If you don't have power at the ballast resistor input side, then trace back upstream from there.

You don't have a choke -- you have fuel injection. If it fires when you dump gas in, then the CPS is good and the throttle body doesn't have a problem. You are confusing people by saying it won't "fire." If you have spark and it starts when you pour gas into the throttle body, it DOES fire. You aren't getting fuel, so it won't stay running. I'm also confused by your statement that it doesn't accelerate. If it only starts when you pour gas into the throttle body, how can you drive it? Accelerate is when you increase the speed of the vehicle on the road. If you can't drive it, you can't accelerate.

Stock is 2-1/2" up to the cat -- and out of the cat. The connector from the cat to the muffler necks down to 2-1/4", and the muffler inlet is 2-1/4". I don't think the change to an HO will make the exhaust sound any different at all. I used to spend a lot of time on trail rides watching different XJs negotiate obstacles, and they all sounded pretty much the same. It isn't very exciting, because with an in-line 6 the power pulses are all perfectly evenly spaced, so the exhaust can never get that lumpy "cammed" sound you get with V8s. I ran a 2-1/2" turbo system on my '88 XJ for awhile and I hated it. It was louder than stock but didn't sound any better, plus it hurt my low-end torque and cost me gas mileage. It was the first (and last) time in my life I actually looked forward to the day when I needed to replace the exhaust system. If you want a Jeep I-6 to sound good ... go Gibson.

The routing has to be different with the XJ proportioning valve. With the MJ metering block, if you eliminate the rear proportioning valve the new single line to the rear comes out the nose of the metering block. The XJ proportioning valve doesn't have an outlet there. For the XJ proportioning valve, the rear brakes get connected to the port you would plug on the MJ metering block. (Bottom/front)

A manual override is much easier. On your schematic, do you see the original radiator sensor? It's a switch. You'll be abandoning it anyway, so you should have a two-conductor plug where the bung sensor connects to the harness. Just plug two wires into that plug and run them to your toggle switch.

No. Proportioning valves are used to alleviate having too much braking at the rear, with resultant premature rear wheel lockup and spin-outs. The easy solution is to use very wimpy (or no) brakes on the rear -- but then you have insufficient brakes when the vehicle is fully loaded.

I still think it's related to the XJ proportioning valve. One of my NAXJA friends always had a very soft peddle in his XJ trail rig. He replaced just about every possible component in the system (except that proportioning valve) to no avail. Finally, he ripped that out and installed a Wilwood manually-adjustable proportioning valve in the line to the rear, and that cured his problem. I don't like the XJ proprtioning valve in XJs, and I think it's a huge mistake to put one on an MJ, but you've already done it so we have to go forward from there.

On the front of the XJ proportioning valve there's a plug, with a vent hole through it and a rubber cap over the vent. Under that is a spring-loaded plunger that does the actual proportioning. The plunger has a rubber O-ring on it. That whole plunger/O-ring gizmo sometimes gets gunked up and won't move, which results in no brakes at the rear. I would start by CAREFULLY (that spring is strong) removing that assembly and swabbing out the bore with brake clearer and Q-Tips. Clean up the plunger, spring and O-ring, then reassemble, re-bleed, and try it.

The reality is that we rarely to never have to actually tap a new hole or thread a new rod, we're always chasing rust and/or burrs out of existing threads ... and nothing destroys dies faster than chasing rusty threads. I'm doing this now on the threads for the caster-adjusting clevises in the lower control arm pockets -- cleaning up the threads so that maybe I can have a fighting chance of getting the flange nuts looses without snapping the studs. Did one side yesterday, I'll do the other side as soon as I get a chance. I think the Harbor Freight sets are ideal for this, because I don't feel nearly as bad chewing up a cheap Chinese die as I would abusing a good American die that way. And we really don't need top quality for chasing out existing threads anyway. Heck, I just checked the Harbor Freight web site. Those 40-piece sets are on sale for $14.99 right now. At that price, if you destroy one tap or die it's almost cheaper to just buy a whole new set than to go out and buy singles. http://www.harborfreight.com/hand-tools/tap-die.html?dir=asc&order=price

I thought you wanted to retain the function of the rear height-sensing valve. If that's correct, you have TWO lines to the rear, and you need to keep them clearly differentiated so you don't totally FUBAR the way your rear brakes [used to] work. See Pete's photo: . The line coming out of the "nose" of the metering block is the one that normally feeds the rear brakes. That feeds into the rear height-sensing valve, and the pressure it sends to the rear gets modulated ("proportioned") by the height-sensing valve. Below that, the one in Pete's photo that has an arrow with the caption cut off has the line removed and a plug installed. That's the outlet for the rear brake bypass, and it normally has a second line going to the rear that goes into the rear lines downstream from the height-sensing valve. The purpose is so that in the event you lose the front brakes, if the bed has no load the height-sensing valve allows almost no braking in the rear. The bypass allows the rear brakes to operate at full pressure if the fronts fail, so you at least have some brakes.

One of the joys of dealing with any of the parts chains is that they can't look up ANYTHING without entering the number of cylinders and whether it's 2WD or 4WD. Taillight bulb? Fuse? Windshield wiper refill? "Can't look it up if you don't tell me whether it's a 4-cylinder or a V-6" Ummm ... right ...

Do NOT use sandpaper, and do NOT use clearcoat. There are specific products out there for polishing plastic lenses. That's what you need. See the write-up in DIY.

Never had typing class in high school. Mea culpa -- but, although I may not be able to type "2001," I can say "two thousand one."

There's a difference between "clear and "pretty much clear." If there was a line of snow between the two worn-down tire tracks in either lane (or a row of snow between the two lanes, it was probably slushy, wet, and heavy. As you switched lanes, running a tire into that line of slush is like slamming on the brakes -- on one wheel. The heavy, mushy snaow grabs the wheel and makes the front end try to slew around.

Yes, but would you trust a used one? Those can be bought anywhere.

More proof that I got screwed on the 2011 XJ I bought for my daughter: Ball joints replaced, TREs and long sleeve replaced (can now adjust toe-in ... YAY!), and the steering is still vague and there are significant clunks emanating from under my feet as I drive it. Not much left -- obviously needs control arms. Called the local dealer to order up a pair of Crowns, which I have bought from them before for the '87 MJ. Parts guy says "No listing." I'd like to support a small, family-owned dealership, but I'm not paying the price for factory parts. So I went away and did some shopping around and found a few sources, but it kept bugging me that Crown would have discontinued a part for the Cherokee (since the same exact part also fits the MJ and the ZJ, and I think even the TJ). I noticed that some of the on-line places list one LCA for the Cherokee from 1984 thru 2001. Other places only list it up to 1996. Odd. So yesterday I called back and asked the guy to see if Crown still has the LCA listed for the '88 MJ. Sure enough, they do. Then he checked the Chrysler listing, and the factory shows the same part for all years, 1984 through 2001. So I ordered a pair. Another lesson in Jeep parts buying. You have to know the vehicle, and don't necessarily blame it on the pothead behind the counter if he can't find a listing for you. It seems some of these aftermarket suppliers don't even know what their parts fit.

Skill had little to do with it. I'm just obstinate. (Ask my wife :) )

Not possible. Your brake line blew because of 25 years of rust.

1987 was during the AMC years. The fasteners are a maddening mix of metric, US coarse and SAE fine threads. Go to Harbor Freight Tools and get two of their 40-piece tap & die sets ... one in metric and one in standard.

You lost traction and fishtailed. Good job catching it before it became a complete spin-out, but in slippery conditions what you do NOT do (not ever) is punch it into passing gear. You drive like there's a raw egg (in its shell) between your right foot and the accelerator peddle. To answer your question about death wobble: It feels like a demented djini has grabbed hold of the front end of your vehicle and is doing his best to fling it and you off the road into the nearest ditch. It is absolutely uncontrollable, and the only way to stop the insane dance the front wheels are doing is to slow down to very nearly a complete stop. It is called "death wobble" because it feels like you ARE going to die ... right then and there.