Jeep won't start

[Homercidal]

Fuel at the rail. Get a small squirt after the pump spins up. Also tried spraying starter fluid in the manifold in case the injectors aren't being fired.

Also get spark at the plug(s) (only checked one). Not a bright blue spark, but a white/yellowish spark. Tested with plug removed and grounded to the engine. I don't have a real spark tester (yet).

Now it cranks good. NO firing at all.

When testing the spark I noticed quite a large amount of spark coming from around the coil-to-distributor wire boot. Like the wire was shorting out back towards the coil housing.

It's been REALLY damp out. Like a fine mist that just hangs in the air and seems to coat everything.

I'm about ready to pull that coil and test and probably just replace anyway, but I wondered if anyone had any other suggestions.

Obviously the computer is allowing spark to be created, and I replaced the crank and cam sensors no too long ago. By bypassing the injectors I think I've eliminated the fuel and injectors as a likely cause.

I had a brief thought of the timing chain being the culprit, but I think the distributor runs on the cam so it's obviously not broken. Maybe skip a tooth, but that is not as likely as it would be with a belt.

Oh, I sprayed WD40 all over the coil. Had a Chevy car that needed a squirt now and again when it was wet out. Still arcing like crazy around the coil boot. Odd since there shouldn't be any real amount of water left on the coil.

 

[jhoneycutt]

Did you check your blinker fluid level? You may just be low. As always use low sulfur DOT3 approved fluid.

 

[Curtis2010]

Type of Jeep?

 

[b-boy]

I had a 1972 Buick Century that did not like moisture. I used to pull the plug wires and distributor cap and put them in a 300F oven and cook the moisture out of them. It seems crazy, and it will smell up your kitchen but it works. Wires could be shot.

 

[flars]

It's been a long, long time. We had tractors that wouldn't start in wet weather. I think we sprayed ether into the coil to dry it out. Pull the coil, bring it inside to dry. Might do the trick. Could also be a broken coil wire.

 

[FlyByNightBrew]

Sounds like you need a new wire that runs from your coil to distributor. If its arcing at the coil you wont get any or weak spark at the plug.

 

[Homercidal]

Did you check your blinker fluid level? You may just be low. As always use low sulfur DOT3 approved fluid.

I doubt it's the blinker level. I had the guy put some in at teh oil change place about 2 months ago. I can't be sure he put the low sulfur stuff in though.

Type of Jeep?

1999 Cherokee 4.0. I got it at a very good price. I paid cash. My cousin, Prince Murray, has a dealership in the valley. He was very good to me.

I had a 1972 Buick Century that did not like moisture. I used to pull the plug wires and distributor cap and put them in a 300F oven and cook the moisture out of them. It seems crazy, and it will smell up your kitchen but it works. Wires could be shot.

Sounds like you need a new wire that runs from your coil to distributor. If its arcing at the coil you wont get any or weak spark at the plug.

Well the plugs and wires should be relatively new. I've replaced them myself. It's not outside the realm of possibility for sure.

I've pulled the coil and am about to test it. After that I may have to look up the procedure for testing plug wires. It's been a few years.

 

[sandyeggoxj]

Se if your crank position sensor is bad. You can sometimes temporarily fix it by cleaning the wire connector and applying fresh dielectric grease. Cps is notorious in these rigs. Next place would be new wires to all the plugs.

 

[brew_ny]

Did you check your blinker fluid level? You may just be low. As always use low sulfur DOT3 approved fluid.

or maybe the muffler bearings

 

[sandyeggoxj]

Also you can disconnect the battery and touch the leads together and then install them back on the battery. That should reset the ecm to default so that it learns conditions again.

 

[Homercidal]

Se if your crank position sensor is bad. You can sometimes temporarily fix it by cleaning the wire connector and applying fresh dielectric grease. Cps is notorious in these rigs. Next place would be new wires to all the plugs.

As far as I can tell it doesn't flag a code. And I was under the assumption that unless the CPS is sending a signal, the engine won't fire the plugs.

Just looked it up and it appears this is correct.

The coil is arcing between the boot and the base of the thingy that juts out from the coil that the wire snaps onto. It's probably an inch from the high voltage contact on the coil and arcing all the way back down to the "base".

Incidentally this is where the 2 pieces of the coil housing meet. There is a sealant that goes between the main housing and the plastic around the wire connector that juts out. It doesn't look like the sealant is disturbed, but it's definitely arcing back to that point.

I'm suspecting there is an issue there. I think the coil tests good otherwise. I get 1.3 across the terminals with multimeter set to 200 Ohms, and 12 through the secondary set at 20K.

 

[ubnserved]

This is a really bad place to get advice on fixing vehicles. But.... 8f it is sparking around a boot a check to make sure it is seated properly some wire sets come with dielectric grease in them and they slip off, some even when the have snapped into place. If that doesn't work take it off and try again. While you have the wire off inspect the area the boot goes over for cracks since electricity will take the path of least resistance it will go that way if it can. After that replace that wire. If you are getting spark at the coil no need to test it, you are only testing for ohms (resistance) anyway it obviously works what is harder to see is any cracks in it. Has your cap and rotor been replaced? If the spark from the coil has no place to go when it gets to the cap it will find a different place.

 

[ubnserved]

You really need a spark tester but you can make due.... the coil wire should have conductivity through it. Take your tester and see if there is. Should also be a certain amount of resistance. (you will have to look it up) be sure to make contact on the metal parts in the ends when testing. Also you will want someone close that can move the wire while you are testing it. You want to move it around to see if it is an intermittent connection.

 

[Homercidal]

Coil wire tests fine.

Odd thing is it was running fine, parked in driveway, didn't use for about a day, and now suddenly it has spark and fuel but won't fire.

Even with a bad coil or wire, I would expect it at least TRY to fire!

 

[ubnserved]

It won't fire if the spark is weak or missing.

So what you are saying is the spark is getting to the plugs now?
And it is not sparking at the coil anymore?

 

[jhoneycutt]

or maybe the muffler bearings

Those are some pesky sons of guns. Gotta keep greased and balanced properly. That was gonna be my next suggestion.

 

[tjpfeister]

Professional mechanic here. If you are arcing like this:

Then there is a crack in the coil insulation and the secondary voltage is shorting back to ground through the primary winding. Very common for old Dodge/Jeep products. Replace the coil. Yes, if you have spark, then you have cam and crank signals at the PCM. (Both common failures on the 4.0L, but both of which result in a stall/no-start symptom)

Cheers

 

[tjpfeister]

You MAY have spark when laying the plug against the head/block because less firing voltage is needed without compression. However, WITH compression, the firing voltage required becomes higher than the voltage required to jump back to the coil.

 

[YeastMode]

+1 for starting with a coil replacement. It sounds to me like an ignition or timing problem, and based on what you said with the spark arching at the coil, I would start there before checking sensors.

 

[TxBrew]

Next thread "I set my Cherokee on fire".

Usually spraying some ether into my CJ7 works fine, albeit not so good for the long-term likely. Like pain killers to solve your bullet wound issue.

 

[brew_ny]

Usually spraying some ether into my CJ7 works fine, albeit not so good for the long-term likely. Like pain killers to solve your bullet wound issue.

always worked in my CJ2A

all the best

S_M

 

[Airplanedoc]

If I suspect that I have sparks leaking via coil, distributor, wires, etc. I open the hood, and crank the engine in the dark. It is much easier to see in the dark where your ignition system is breaking down. It sounds like you have replaced the wires, so I would suspect the coil or coils. I have seen entire lightening shows under the hood of old jeeps this way.

 

[YeastMode]

I have seen entire lightening shows under the hood of old jeeps this way.

And older Chevy Vortec V8s. My neighbor has one and I feel like we are chasing an electrical problem once a year. So we take a look at night, looks like someone setting off fireworks with all the leaky plug wires.

 

[Homercidal]

Professional mechanic here. If you are arcing like this:

Then there is a crack in the coil insulation and the secondary voltage is shorting back to ground through the primary winding. Very common for old Dodge/Jeep products. Replace the coil. Yes, if you have spark, then you have cam and crank signals at the PCM. (Both common failures on the 4.0L, but both of which result in a stall/no-start symptom)

Cheers

That's exactly where it's arcing. I noticed it after replacing the plug and having the kid crank the engine.

I pulled the dist cap and it looks nice and dry in there, but for the money I may just replace that and the rotor when I replace the coil.

This kind of really damp weather is unusual here. We may get it like this a few days a year at most. usually in the spring or late fall but only if the conditions are just right.

I'll be picking up the parts today and I will report back when I have a chance to swap them in. I might get a spark tester while I'm at the store. I have had need for one a couple of times this year already for various friends and family.

 

[Dopeybrew]

1999 Cherokee 4.0. I got it at a very good price. I paid cash. My cousin, Prince Murray, has a dealership in the valley. He was very good to me.

 

[Homercidal]

Put a new coil in last night. Was very busy so I put it in and tried and it kind of wants to fire now, but it just doesn't actually start. Really feels like a timing issue. These have a chain and gear, and I've never heard of them jumping teeth, especially when it drives perfectly fine into the driveway one day and then doesn't start the next day.

I guess I should check for TDC and distributor position and verify that it's on target before towing to the shop. Probably should pull and check all plugs and wires too. I wish it had died inside the garage. I may think about hooking a strap to the Durango and pulling it over to the garage. It's getting cold out.

 

[tjpfeister]

Just so we are clear: There is nothing worse than trying to diagnose a car over the phone or the interwebs. With that said, there are some quick checks/tests/things to rule out.

First- You stated that the ignition short was arcing through the boot of the ignition cable and back to the coil, right? This tells you that the insulation of the wire is bad. This is one reason to condemn it. However, it should still fire unless there is high resistance elsewhere (through the coil wire, or a multitude of the other wires). Check resistance with an ohm meter (harbor freight gives these away, literally.) Expect to find approximately 1000 ohms (1k ohm) per foot of cable; APPROXIMATELY. Or test with known good part.

Two- Make certain your plugs aren't fouled. Might as well pull them and inspect them because it will lead into point number three. If the plugs are wet, i like to hit them with some brake clean and then a flame. Also, sniff the dipstick. If the oil has been contaminated with too much fuel, this will lower compression and warrants a minimum of a dump-n-fill.

Three - since the plugs are out, bring #1 up to TDC compression and see if the distributor rotor is pointing directly at #1 on the cap. If this is off, then you might suspect jumped time... But I have never seen a 4.0L jump time. While you are at it, put your meat-hook on the rotor and see how much play there is. Any significant play and it warrants pulling the distributor for inspection. These do wear, there's a brass bushing that goes if I remember right. This can cause ignition timing issues but usually is accompanied by a sqeauling sound underhood prior to failure. (you wouldn't ignore something like that, would you? radio volume UP)

Cheers and good luck, back to work I go. Oh, for what it's worth. You can cycle the key to get codes on your rig. I think it's On-off-on-off-on-off-on (but google it to double check me). This will display the codes in the cluster. Run the codes through google and see if you get anything pointing towards cam/crank signals (but I doubt it, since you have spark)

 

[Curtis2010]

Se if your crank position sensor is bad. You can sometimes temporarily fix it by cleaning the wire connector and applying fresh dielectric grease. Cps is notorious in these rigs. Next place would be new wires to all the plugs.

Sounds like you've got some wiring issues, but yes the CPS is a common problem. If it goes bad the Jeep won't start, period.

One of my other hobbies is my '89 Jeep XJ (4.0 RENIX). The RENIX system is a relatively simple control system. Most troubleshooting can be done with just a multimeter. I carry full set of spare sensors and an ECU just in case. Some very good maintenance and troubleshooting tips from a former tech below.

http://www.jeepforum.com/forum/f140/cruisers-mostly-renix-tips-1304879/

JeepForum is a very good source of Jeep info.

 

[krackin]

Do a complete tune up kit and go from there, cap to plugs. Simple start to a probable and hopeful simple finish.

 

[YeastMode]

I had one of these for a while, and just like everyone else that did, I spend my fair share of time working on the car (fun fact: my grand Cherokee almost caught on fire because of a relay melting down in the rear gate! But I digress...).

I would think that a timing issue is unlikely, unless you moved the distributor, as you stated that the car dove fine until it would not start again. You also stated that you had fuel through the injectors, so for the time being I am ruling out fuel pump and filter, for now. So, I would replace the coil (which you have) and then I would replace all the wires and plugs. I would then double check TDC/Distributor position, and see what happens. At that point, you should have no ignition problems.

I think that you will fix your problem with changing the wires. If not, report back, as I am now genuinely curious as to what gremlin has made residence in your jeep.