PLEASE HELP!! Hard/No Start - NEED EXPERT ADVICE!!

Basics: 96 XJ, 4.0, AX-15, 181k miles, bone stock.

I APOLOGIZE IN ADVANCE FOR LENGTH OF POST! But I did want to be thorough and include test results…I have searched and done my testing! ALSO, to anyone who can help, thanks in advance and I PROMISE to follow up with what resolves the problem!




Hard starting issue - only during heat-soak period of maybe 5-45 minutes AFTER hot shutdown. An IMMEDIATE restart is not an issue. Only when the engine has had time to "soak" after a nice hot drive do I have the issue. On cold starts, the engine cranks right over. It seems to me I am having vapor-lock type issues. When I have the hard start condition, the fuel coming out of the fuel rail test port is bubbling and under high pressure. I have thoroughly checked the area around each injector and have found no fuel leaks whatsoever, even when wiggling each injector and running the engine at 3k+ rpms.

It seems this issue has slowly gotten worse. I don’t recall having this issue last summer. I was having funny fuel delivery problems several months ago which appeared to be vapor-lock. I tracked down a hot run condition (temp would easily climb to 220-230 in a lot of idling or wheeling) to the fan clutch, which was shot! Now it roars, literally, and I thought my fuel delivery issues were solved.

Brand new fuel cap. Nearly new fuel filter, within 1k miles. (OLD WAS NASTY!!) Air filter fine. No CEL or codes.

Engine runs very strong and climbs smoothly. Never really idled like a Lexus, but not much different than any older domestic. With 181k miles, I don’t expect a brand new car.

As far as symptoms, sometimes it is a long start with a roughness for a couple of seconds after finally starting. One good push of the throttle clears it right up and it runs normally...Cool fuel now flowing??

Sometimes, it won't start at all on its own. Then I need to shoot some starter fluid in the intake, open the throttle, and crank. It will eventually turn over with the roughness then clear right up. Cool fuel now flowing??

It does start with a bit of richness out of the exhaust when I experience the longer starts, even without starter fluid.

Fuel pressure gauge shows rapid fluctuation during all running conditions (idle, part, or full throttle) of 48-52 consistently at any temperature. Now, I have read many different things about the proper numbers. 48-52 with a rapid flopping of the needle sounds normal. I have heard different things about the leak-down pressure. HERE I read lower than 30 psi within 5 minutes and HERE I read 24 in 5. I tend to believe the 24, since it specifically states my 96 model year and the 30 seems to be people referring to the 97-01s. QUESTION: Does the leak-test have to be performed immediately after turning off the motor OR can the leak-test be done at anytime, as long as you place the key in the run position and begin the 5 minute countdown?

I performed the test several times. Each time, immediately after shutdown, I have 47 psi. Over the 5 minutes, it never drops below 44, and sometimes climbs back up to 47 or 48. Even though I just shut down a motor that was running at 195-205 (dash gauge, no IR, sorry!), the fuel rail wasn’t too hot.

Here’s where the problem is: I allow the engine to heat soak and check the pressure between 5-45 minutes after shut down. I turn the key on and pressure always comes right up to 44-46 psi. I start the clock watch. The pressure drops VERY fast!!

Approx 10-15 minutes after nice hot shut down…Hood was left open too!


TIME (minutes)- PSI


START- 44-46
.30- 42
1:00- 39
1:30- 36
2:00- 33.5
2:30- 30
3:00- 27
3:30- 23
4:00- 22
4:30- 19
5:00- 19


Approx 20-25 minutes after hot shut down…left hood closed…


TIME (minutes)- PSI


START- 44-46
.30- 36
1:00- 29
1:30- 25
2:00- 22
2:30- 21
3:00- 20
3:30- 18.5
4:00- 17
4:30- 15
5:00- 11


So, assuming I am testing it properly (okay to test even if engine wasn’t just running) I am WAY below both the 30 psi and the 24 psi. I think the fuel in the rail is still nice and cool immediately after shutdown, hence the nice strong pressure the first 5 minutes after shut down.

Out of the possibilities available, I think I can rule out a lot. New fuel cap – tried 2 different brands just to be sure! Don't think it's an air issue...I have tried opening the throttle up for 10 seconds before starting to let air fill before cranking...doesn't help. Fuel pump seems to be very consistent and putting out adequate pressure. Check valve/pressure regulator assembly is in the tank, correct? If so, that rules that out as the problem is directly related to heat soak. Not sure if any of the sensors could cause something like this...IAC, TPS, MAP, O2, etc., but from my little knowledge on those sensors, I'm thinking no. So, because of the leak down, the only thing this leaves me with is a leaky injector, right? I have read stories of an injector leaking into a cylinder and flooding a cylinder, causing a leak down condition. Could this only happen when hot? Maybe a seal inside of the injector? This could also explain rich exhaust…

Maybe my period of "overheating" further rotted aging injectors or their seals?

Love to hear what you guys think….If you made it this far, thanks again for reading it all!

I can't believe it...not one reply??

Guess I'll *Bump* it...:wow: :wantyou: :eyes:

Reply

Sorry I can't be more helpful. I just don't know, was hoping to learn something.

I am no expert, but I thought the fuel pressure regulator was on the fuel rail on the 96 model year...when I checked rockauto.com for parts, they show a picture of one that looks like it mounts on the fuel rail....

McQue said:

I am no expert, but I thought the fuel pressure regulator was on the fuel rail on the 96 model year...when I checked rockauto.com for parts, they show a picture of one that looks like it mounts on the fuel rail....

Click to expand...

From what I understand, pre-96 had inline regulators...also run at a lower pressure too.

Anyone who is interested should also follow me on this thread...

http://www.jeepforum.com/forum/showthread.php?p=5048257&posted=1#post5048257

Just read through my 01 FSM and it states the fuel pressure checks should be done at normal engine operating temperature...
Connect you pressure gauge with a TEE connector so that you can clamp off the line on either side of the gauge....
Once you are at operating temp, shut off engine...check pressure...
If you clamp off the line before the gauge and it bleeds down too quickly, you have an injector problem...If you clamp off after the gauge and it bleeds down too quickly, you have a fuel pump/pressure regulator/check valve problem.

You have done some good trouble shooting......Just take it some were that you trust. I dont like to do that my self but when you get so into trying to find the problem sometimes sight can be lost and you can over look things. I am in FL also if you are near orlando i can give you my guys # he works on my 1988 XJ and our 1956 chevy (show car). Let me know if you want that # ?

McQue said:

Just read through my 01 FSM and it states the fuel pressure checks should be done at normal engine operating temperature...
Connect you pressure gauge with a TEE connector so that you can clamp off the line on either side of the gauge....
Once you are at operating temp, shut off engine...check pressure...
If you clamp off the line before the gauge and it bleeds down too quickly, you have an injector problem...If you clamp off after the gauge and it bleeds down too quickly, you have a fuel pump/pressure regulator/check valve problem.

Click to expand...

When I run the motor and shut it down, my pressure stays great for 5+ minutes. I mean, at shutdown, it's 44-46, and it might not drop below 42 before fluctuating back up to 46-48. Only when I test it during the heat soak period (5-45 mins after a hot run) do I notice a leak down below the spec of 24 psi in 5 minutes. Either way, I've heard leak down is very common on older XJs and not much to worry about.

Maybe I'll try to pinch the rubber line at the start of the fuel rail and see if I get some different leak down numbers...

Please check out this other thread I have going. There are 4 or 5 pgs of troubleshooting and educated guesses...worth checking out for sure. I would love to hear ideas after poking through that...

http://www.jeepforum.com/forum/showthread.php?p=5049778#post5049778


78/xj88,
Thanks for the offer....I may have to take you up on that! I am actually moving to Lake County area from treasure coast area, so it could be an option...I'll let you know if it gets to that! :hang:

Good Luck !
When it comes to my XJ starting up i spare no expense !!!

So I am almost positive I have a bad coil. I say almost positive, because I haven't replaced it yet to see if it is definitely solved. But here are some pictures of what I found this morning. Now, these pictures are after degreasing the side of the motor 3 times!!














You can clearly see the huge crack on the side, but there is also some cracking on the top, too. This was a big indicator.

Now, going off Country Boy's suggestion on the Jeep Forum post that a motor will still fire with ether even with a poor spark, things started coming together. I also had a guy here (http://jeeptalk.net/index.php?showtopic=11177) mention how his coil was cracked, which made me take a closer look and find the above.

I drove the XJ and got it nice and hot. Let it sit for a while, then tried to fire it up. Nothing. Had a helper crank while I checked for spark...Nothing. Wow. So I reach over and grab my nice cold Aquafina bottle. I pour some on the coil. Crank it please. Bam, fires right up.

I now need to decide what to replace it with. AAP has a BWD coil for $30, which I was tempted to buy today. But they also have an Accel available for just $40. Then, of course, I can search the web for deals.

I am not in a position to spend $200 to do a real upgrade. I know Performance Distributors makes their firepower kit (and many many more companies and kits), which sound cool, but I have Autolite Pro series wires from AAP, which are lifetime warranty. So I can get a free set of those when I do the coil, clean up the cap and rotor I've got, buy some new plugs (Maybe Champ Truck or Platinum) and be done for under $50. So, I guess I need to start reasearching coils...can get by with this one for now, but who knows how long it'll be before it dies on the highway or some other unsafe place.
I would love some advice on my coil/plug purchase, but don't want this thread to become a free-for-all...I know we can get 100 people and each one just LOVES this plug or that plug. I will definitely search through the old posts on plugs and check for some coil info too.....

As a side note, I also took the opportunity to clean the intake manifold (w/Seafoam) and removed the TB and cleaned that. Both were horribly filthy, and I already notice a very slight improvement in idle and throttle response. I will follow up with a full description and report of what I did and the results in a few days.

I will definitely post a final follow-up on the results here...


A HUGE THANKS AGAIN TO EVERYONE WHO TOOK THE TIME TO RESPOND AND TRY TO HELP - YOU GUYS ROCK!!

Okay, so yesterday I went ahead and installed the new coil from AAP, along with some new wires. I thought the cap and rotor were replaced right before I bought the XJ (1 year ago), so I had no plans to replace them this time around. Well, let's just say they were in bad shape. I will post pictures of them soon.

So, needless to say, I ended up doing the coil, wires, cap, rotor and plugs. After doing the work, the XJ started fine, although I was expecting that I would get faster starting w/my nice new spark.

So I drove to AAP to return something and when I came out....NOTHING!! Crank, crank, crank!! Got someone to crank while I pulled a wire....NO SPARK!! I ended up spraying a shot of starter fluid into the TB (which fired her right up) to get it started!!

So, I really need some help now guys. What else could I be looking at. Let's remember, it's only when it's heat-soaked....runs fine any other time...

NOTE TO MOD:

Can you please add to the thread title:

NEW COIL, STILL NO SPARK WHEN HEAT-SOAKED!!


Thank You!! :helpme:

i'd start a new thread on that.
intermittent no spark = cps?

Pictures, as promised....




Cap...Look at that corrosion!

Underside - Corrosion and almost nothing left of the center contact!!

Wire - More corrosion on coil to cap wire

Coil - Hard to see it, but there were serious cracks on every side of the coil!!

sorry nevermind...
Good luck my 88 is having it own fit now so......
Seafoam for her...
Keep us updated

The bad coil may have damaged the ICM directly under the HV coil. Borrow a known good ICM and test it out. What coil did you buy? They have been know to go bad right off the shelf.

Based on your tests it also sounds like you have a leaking when heat soaked injector. Seems I read about a specific injector on some later years had problems with the head of the injector touching the intake manifold, or something like that and the fuel boiled in the injector causing problems like yours on a heat soaked restart. That drop in fuel pressure only when heat soaked is a dead givaway.

Have you checked the Ballast resistor, ballast resitor relay and fuel pump relays in the fuel/ECU circuits?

Ecomike said:

The bad coil may have damaged the ICM directly under the HV coil. Borrow a known good ICM and test it out. What coil did you buy? They have been know to go bad right off the shelf.

Based on your tests it also sounds like you have a leaking when heat soaked injector. Seems I read about a specific injector on some later years had problems with the head of the injector touching the intake manifold, or something like that and the fuel boiled in the injector causing problems like yours on a heat soaked restart. That drop in fuel pressure only when heat soaked is a dead givaway.

Have you checked the Ballast resistor, ballast resitor relay and fuel pump relays in the fuel/ECU circuits?

Click to expand...

Hey man, thanks for the reply! The coil is a BWD from Advance Auto. I don't necessarily trust "brand new" parts, but for the new one to die when heat soaked and work fine any other time would be too much of a coincidence, I think.

I would definitely agree with you that I could easily have a leaking injector. Based on age and mileage, I would almost assume 1 or more do. I just don't think that's what's causing this issue, since I am not getting spark when heat soaked. You may be thinking of the injector 3 issue on the 97-01's, which I read quite a bit about. Only thing is, my XJ hasn't always done this.

As far as FP relay, I have jumped it and still have the issue. Do I have a ballast resistor on my 96? If so, where is it and how do I test?

Also, where is the ICM?? Is that within the distributor?

I had someone on that other thread (I mentioned above) mention the pickup in the distributor (CAS??). I have also thought it could be a CKS.

Bottom line is I only have the problem after a nice heat soak and if I shoot some starter fluid in the TB, it starts and runs fine after a little stumbling. Makes you think "fuel", right? But I've checked and I don't get spark when I have the no start....

And to top it all off, now I've got a really bad leaking axle seal spraying gear oil all over my brand new front pad and rotor...when will it all end!! :bawl: