Won't start... HELP please!

So while down at the gorge last week, I broke down, long story short, water pump and alternator both went out with the alternator freezing solid which resulted in breaking my serpentine belt right on the trail. After getting towed back to town, I was in a hurry trying to get my alternator off and forgot to remove the positive from the battery. Of course I touched my ratchet to the unibody and arc-ed it. Then after getting the alternator out it turned out that the parts store didnt have an alternator anyway so my buddy towed me all the way home. After getting home, i replaced the water pump and alternator and put the new belt on and then attempted to start it up. It started ran very poorly for about 5-10 seconds then died and wouldnt start again, I let it sit that night and the next day it still just cranked but no start, after doing some research and unplugging the harness to the CPS then turning the key on then re-hooking up the CPS harness the jeep started then died again and wouldnt start back up. I decided to change the CPS and of course this didnt fix the problem. So there are a ton of things I could start with, but does anyone have any ideas as to where and what to start with?

Thanks
Rick

Wanna share about your Jeep ? Year, engine, transmission, etc.

Of course that would help huh? 1986 XJ wagoneer with 4.0L renix from an 88 XJ.. Engine block is a 1996 all the top end is the renix stuff from the 88. Aw4 with NP231 any other info u need just let me know.. Everything in he cab is 1986 stuff from the bulkhead out is all 88 stuff including the whole entire drivetrain and suspension and engine wiring harness.

Thanks
Rick

From the sound of things it sounds probable you burnt up a fusible link. That would be the first thing I'd look at. Then check for spark and fuel.
Needs three thing to start, spark, fuel and air. Spark will tell you the CPS is likely good. Start then die as soon as (or shortly after) you stop cranking usually means the ballast resistor is bad.
If it spewed coolant all over the motor you may have other problems, coolant is worse than water for electrical mischief.

My strategy for a no-start is always the same.

Job #1 is to check for spark.

Remove a spark plug, keep it attached to the plug wire, place the plug electrode near a good engine ground, have a buddy crank the engine while you watch. You are looking for a strong, blue, snapping spark. Yellow/orange/white indicates a weak spark, which may not be strong enough to start the engine.

If spark quality is good, try spraying a small amount of starting fluid into the intake. If the engine starts and runs momentarily, you have identified a fuel delivery problem TO the fuel injectors.

Once you have answers to the "what am I missing" questions which you can get with the above two techniques, the suspect list gets a whole lot shorter.

Post back what you find!

Ok so I pulled a plug and it was completely black and i put a new plug in and the spark was good. I replaced the plugs,rotor and cap and it started and ran fine except it is idling at 3000 rpm and after about 20 sec the idle started going up so I turned it off. There is black smoke coming out of the tail pipe pretty badly.. I'm on my way to pick up the coolant temp sensor to replace mine.. I'm not sure it's bad but I've read if it's bad it can make it run too rich... Anyone else have any other ideas for what to check regarding the idle?

Most every time I've had that 3000 RPM idle it was after the TPS got a bath, either a mud hole or an engine wash. Possible the vacuum line for the brake booster is open, that will run the idle up pretty high, I don't think it will make three grand though.
A broken throttle return spring is always a possibility or a broken throttle plate spring, sticky throttle cable. Or anything that allows the engine vacuum to pull the throttle plate open when no gas pedal is pushed.
A Bad Map (or no MAP vacuum) can make it run really rich, but in my experience won't cause the idle to go up.

So does that mean I need to replace the TPS, I am not really sure that it got a bath, actually I would say that it didnt. I am considering the following culprits at this time. A vacuum leak, MAP sensor/vacuum leak, TPS and Idle Air Control Valve. I already have a new CPS and Oxygen sensor. I also thought about removing all of the hard lines and replacing with flexible vacuum lines. Anybody have any thoughts on any of this? I am considering just replacing all three so that I know they are good for sure then going from there or is this not how I should go about it? i want this to be my daily driver so I don't want to have a bad sensor every month.

I guess the first thin I should do is check all the vacuum lines for leaks and attachment and go from there before I start throwing sensors at it. So has anybody done the flexible vacuum lines or should I just get a replacement vacuum line set?

i went with mostly all flexible lines. i left the CCV hard line and the MAP hard line. i also eliminated most of all the crap that is not needed. make sure you keep the vacuum bottle hooked into the HVAC stuff or your heater will be doing funny things all the time. flexible lines are the way to go under our hoods due to the temps we run. the hard lines usually get brittle and crack without you knowing it. on another note id check the TPS and IAC along with all vacuum stuff before throwing anymore parts at it. grounds are also a good place to look also. you never know with these money pits.

You need a serious vacuum leak to get 3000 RPM's. The small vacuum connections IMO aren't enough to do it. Maybe a large vacuum connection like the brake booster or the vacuum line running to the canister, but again if I remember correctly even with one open, it won't make 3000 RPM.
When I suspect a vacuum leak I cut some short pieces of tubing to fit, put a crew or bolt in the end and plug off everything except the fuel regulator and the MAP. Reconnect them one at a time and see what happens.
Some unlikely but possible causes could be the screws for the throttle body being loose. Or the little (wiper) arm for the TPS being stuck.
TPS is fairly easy to check, the three wire connector. The test has been written up many times and the expected values posted.
Don't neglect to look down the throat of the TB and see what position your throttle plate is in.
If you replace the vacuum lines use a thick walled flexible line designed for vacuum. Thinner wall flexible line can suck shut.
It is always a good idea to re-torque the intake/exhaust manifold bolts, though again it is doubtful they would be loose enough to hit 3000 RPM. Be careful with the re torque don't snap anything off, especially the end studs, they snap easy.
I'd look in the TB and check the throttle plate position and test the TPS (three wire connector).
Maybe someone could disconnect their TPS with the motor running and see what happens (my 88 isn't running right now, parked with the battery out). My guess would be not much, until you applied some throttle. Unplug yours and see what happens.
You can eliminate the IAC by putting your finger over the air opening and see if your idle comes down.
I don't replace anything I don't have to, I've even been known to dry out a TPS on/near some heat for a couple of weeks and use it again.LOL
I Have another set of junk yard sensors and modules I use for testing, they fit in a fairly small plastic toolbox I carry with me. New isn't necessarily better, I'm still using some sensors from 1987.
Good luck, been there done that.

Great Tips! On the IAC if I block the hole should the idle come down if the sensor is working properly or if the sensor is malfunctioning? Keep the ideas coming everybody!

Thanks
Rick

Possible it is stuck all the way open, most times it just needs to be removed cleaned and oiled a little. Though I doubt it being stuck all the way open will get 3000 RPM. If you do clean it, make sure it is disconnected with the key off. Don't even try to move the piston/plunger or whatever it is called. Clean the seat out. Even if that isn't the cause of your grief it likely needs to be done anyway.

First thing I found was that the vacuum line to the MAP sensor was broke in two. Second two other vacuum lines were completely disconnected. So I hooked all of those up and started it and it runs a lot better and not rich any more but the idle still stays at 2700 and goes up to 3000 every 20-25 seconds then back down to 2700. So I took off the IAC valve and cleaned it really good then oiled it up. It looks almost new. I hooked it back up cleaned all of the terminals with electric cleaner and it still idles at same speed 2700-3000 so i decided to pull of the harness to the IAC while it was idling and it did absolutely nothing and kept doing what it was doing. Does this mean that The IAC is bad?

Stuck all the way open, it isn't likely you'll get 2700-3000, the hole through the IAC isn't big enough for that IMO (maybe, I've never seen one stuck all the way open). Cover the IAC intake hole up with your finger (and a glove) and see what happens.
I'd look down the TB and see what position the throttle plate is in, should be none, to very little gap between the butterfly (throttle plate) and the TB wall. I'd try unplugging the TPS, with the motor running and see what happens.

Ok, so this is the steps I should try.. correct me if something is not right. Remove the IAC again and cover hole while idling and if the idle drops then the IAC is bad and replace? Second, Unplug the TPS while idling and see what happens, what should I expect if it is good/bad?, and inspect and adjust the butterfly in the throttle body to make sure it is seated properly, also remove TB and clean if it is super dirty. Should I shine a light in the IAC hole and look for carbon build up in there? If it is gummed up should I go ahead and remove the TB and clean the whole thing? Should I take the TPS off when I clean the TB or just cover it up with something while I clean it and what should I use to clean it?

I'm guessing you have a Renix TB, the *in* air for the IAC is a squarish hole on the top of the TB, put your finger over the hole.
Look at the position of the throttle plate when the motor is running, it should be closed, unless somebody pushes the gas pedal or something is screwed up.
Cleaning the whole TB is a waste of time, in my experience, most of the gunk is in the IAC and the IAC air passageways. If you do take it off to clean it, keep the solvent away from the TPS. If you remove TPS (which is safer) you have to adjust it again and hopefully you don't snap the TPS hold down screws off. Cleaning the TB on the Jeep just washes all the crap down the intake. Removing the TB, sometimes ruins the gasket.

You can look down the IAC *air in* hole with a flashlight and see the piston tip I believe (I'm too lazy to go out in the garage and look see for sure ). You may be able to tell if it is open or closed. It usually parks itself around 1500-2000 RPMs and mostly closes as soon as the motor is running (hopefully).

I've only replaced one IAC in my life and that was one I ruined trying to move the piston. Whatever you don't plug it in with the ignition on and with it out if the TB, I launched one clear across the shop. I clean it up and let a drop or two of synthetic oil run behind the piston, then do it again next year. The last one I bought new was around $60 and that was a long time ago.

Sorry if you are having a hard time with my tips and suggestions. I have no way of knowing your skill level, I kind of shoot for the middle, not too simple, not too complicated.

So if the passage way that you put the piston into looks black then I should clean it off the jeep right but just keep cleaner away from the TPS? Is it just a matter of spraying cleaner into the hole and letting it run out the other side? Will brake cleaner work? Am I correct that if I cover the hole and the idle lowers that the IAC is bad or does it just mean I have some cleaning to do? I am mechanically capable to follow any instructions to complete a task, I just dont have much experience with the RENIX system and I want to make sure I am doing this stuff right so I dont Cost myself more money or Cause myself more problems than I have too, I appreciate your advice. Would you say there is a write up on here somewhere that has details on the process of cleaning the IAC and it's passage ways?

I've cleaned it on the Jeep and off, depends on how much stuff is caked in there, I try to avoid washing stuff down the intake. I squirt it out with brake cleaner or Liquid Wrench (which works better) scrub a little and scrape a little with something that won't scratch the piston seat, like a piece of wood or plastic. I have a little round brush that fits in there (nylon gun bore brush).
Squirt a little spray oil so it runs behind the piston, shake it out. Then I put a few drops of synthetic oil and let it run behind the piston in the IAC.
Usually when the IAC sticks, it sticks closed in the buildup on the piston and the seat. If it sticks open it is usually from grime behind the piston. In back of the piston there is grease, a threaded rod and a tiny motor. The grease gets thick with grime and crust. Physically moving the piston around can damage things, tiny gear motor etc.
I'd try cleaning it before I replaced it (they're not cheap), I've cleaned them and had them work for years. Your problem may have little to do with the IAC, it would be bad if you bought a new one you didn't really need. I've never seen an IAC stick open and cause a 3000 RPM idle (I guess anything is possible), I have seen a shorted TPS do it though. I've seen the IAC stick closed (zero idle), I've seen them stick open momentarily and cause a 1500-2000 RPM surge (it's called the Renix hot start, pretty common).

butterfly valve is seated good.. I unplugged the TPS while idling and the idle didn't change at all.. does this mean the TPS is bad?