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By YJ Bill - 6/23/2010 11:42:36 AM
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Nate, I would rule out oil pressure as the cause, a 4.0 does not have an oil psi shutoff to the best of my knowledge, most vehicles that do have it on the low side for when you burn all the oil and loose pressure
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By Tigger - 6/24/2010 2:32:52 AM
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My CPS caused similar issues on my Durango, but after about the 4th time, it just wouldn't start.
The TPS could cause that as well.
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By jerreyjeep - 6/26/2010 3:38:58 AM
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on a side note: check/replace your fuel filter anyway. if ya ran the tank dry it coulda sucked some crap off the bottom of the tank.....same kinda thing happened to me on another vehicle...........drove me nuts untill I found the filter was my problem.
ps: my oil press is usually pegged while running!...jeep sensors are not reliable.
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By bobcat481 - 6/27/2010 9:47:31 AM
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I had the exact same proplems with the 7.3 in my F-250. A sporatic proplem that threw NO codes and would kill the engine completly. Then it would re-fire almost immediatly (until it burnt a computer up). It turned out, after buring up 2 IDM's, that it was a ground issue. The computers need a clean ground reference, and the various ones on my firewall were the culprit. (after a couple of bouts with this, I narrowed it down to a single one.) The trouble child I found has to be bright-ass-clean. It will still act up every once in a while to this day, and I have to re-clean the ground. I have tried anti-ox on it and everything. Totally different vehicle, but something to think about. Also, with low fuel, could you have sucked a chuck of crap up out of the tank? Just a thought. Later
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By NakedJeeper - 6/28/2010 1:09:57 AM
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YJ Nate (6/24/2010)
Found a few things online that mention the CPS and TPS both being causes of similar issues... Does this make sense to anyone out there?
My 98 TJ had TPS issues that took a couple of months for the dealer to find/resolve during that first year. It would stall occasionally on the freeway and be hard to restart. Never hard to start when cold. Never stalled in town at slow speeds. It never really through a TPS code, but it would be a misfire or other code instead. New TPS and trouble free since.
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By kg6dfh - 6/28/2010 10:46:07 AM
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Had a similar issue with my CJ. Under load, it would stall. Sit a second, start right back up. My problem was the fuel line on top of the tank. It was old, and collapsing, pinching off the fuel supply. Once it stalled, pressure would release the collapsed line, and let fuel flow again.
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By artyart - 7/22/2010 8:41:44 AM
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YJ Nate (6/24/2010)
Found a few things online that mention the CPS and TPS both being causes of similar issues... Does this make sense to anyone out there?
yes, maybe the crank sensor... possibly the throttle sensor is nort working well or has a dead spot in it....before you do that, you may want to check for vapor, OR see if there is a lot of debris, crud buildup in the fuel rail, that caused me a huge now ya see it now ya don't issue for a while.... all it will cost is some injector o rings (cheap)
Oil pressure when running would be around 45-50lbs maybe 60, warmed up at idle it should show around 25-30. It wouldnt cause what you are experiencing
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By YJ Nate - 6/23/2010 8:21:41 AM
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Odd issue cropped up today...
92 YJ, 4.0, Manual
Jeep was running fine the last time i had it out.
Since then i've changed the oil, and adjusted the parking brake.
Today i took it out for a short trip. About 10 miles out, 10 miles back. (all on pavement)
On the way out, i was coming down a hill, in gear, using the engine to keep my speed constant. Got to the bottom of the hill, and pushed in the clutch to stop, to find that the motor had cut out.
My gas guage doesnt work, and i knew i was low, so i assumed i was out of gas. It didnt seem quite right to me though, as there was no stuttering. Turn the key, i still hear the fuel pump engage. So that's fine.
I called my wife, who was 2 blocks away (thats where i was going, her parents place). She brought gas, i put it in the jeep, fired right up, i figure problem solved.
When i went to go home however... After the first 5 min or so of driving, the motor cut out. This time i was on the throttle, going up a grade.
I pull over, try to restart nothing. I turn off the ignition, wait a few minutes thinking about the situation, it starts up!
I thought maybe this was related to the earlier "gas" mishap. Didnt quite add up to me though. Air in the gas line? Nah, i wouldnt have gotten _that_ far on what was in the line...
So i decided to trek on. I made it about a minute, again, on the throttle. And it cuts out again. This time i left the ignition on and pulled over. let it set a few minutes, turned the ignition, wont start.
Turned off the ignition, waited a minute or two, started right up.
I did this routine a few more times. getting about a minute or run-time per attempt. Then i was finally at the top of the grade, and was able to try coasting. I fired it up again, got up some speed, and then took it out of gear and coasted.
I got about 7 minutes of run-time out of it, which got me to the bottom of the hill. Sure enough after i started getting on the throttle again, it cut out again.
This time i tried keeping RPM's down, and i seemed to have better luck. I could get some distance at low rpm's (under 2K).
Something i noticed is that the oil pressure seems higher than i remember it.
Right now i'm letting it cool, and i'm going to check the oil level, to see if its high. If it is i'll drain some and see if that helps.
Any other suggestions on what this might be?
I seem to remember the oil pressre guage staying around 40 once the motor was warmed up, now it rides around 60. Can anyone confirm if this is higher than normal?
Thanks!
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By YJ Nate - 6/23/2010 9:46:12 AM
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Ok, i checked the oil, its not overfull. Well, its just slightly over the top "safe" line on the stick, but the motor was still just slightly warm when i checked it. I'll check it again tomorrow after its sat for a while.
I let it idle in the driveway for a while, not so much as a stumble.
I revved the engine up as high as 2500 rpms, and let it stay there for a bit, the oil pressure peaked at about 60, and the motor did not cut out.
I took it out for a ride. Through town, (no higher than 3rd gear) all was well, as soon as i got to an open road, it stalled out twice as soon as i hit 4th gear. Both times will on an uphill. When i was taking it back home (going back down hill on the same open road) i did not get any stalls in 4th.
This feels like its either an electrical problem, loose ground or something. Or some kind of safety cut off. Is there such a beast on a 92 4.0?
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By bob91yj - 6/23/2010 11:20:02 PM
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Did you mess with the parking brake pedal? If so, there is a ground wire at the pedal mount that grounds the fuel pump system. If you have a loose connection, it can cause your symptoms.
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By YJ Nate - 6/24/2010 12:42:20 AM
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bob91yj (6/24/2010)
Did you mess with the parking brake pedal? If so, there is a ground wire at the pedal mount that grounds the fuel pump system. If you have a loose connection, it can cause your symptoms.
The pedal itself was not touched. Other than general operation of the pedal, which has not changed. Even when the brake hardly worked, i still used it.
I'll check anyway, thanks!
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By YJ Nate - 6/24/2010 12:58:32 AM
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This thread on vapor lock: http://www.jeepsunlimited.com/forums/showthread.php?t=478979
Doesn't really describe what i'm experiencing.
The jeep runs perfectly until it cuts out...
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By YJ Nate - 6/24/2010 1:13:20 AM
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A friend pointed me at the following article:
http://www.best-jeep-guide.com/jeep-stalling-while-driving.html
Maybe the fuel pressure regulator?
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By YJ Nate - 6/24/2010 1:57:34 AM
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Found a few things online that mention the CPS and TPS both being causes of similar issues... Does this make sense to anyone out there?
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By YJ Nate - 6/24/2010 11:09:23 AM
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Well, it's not vapor lock. I hit that little release on the fuel rail, and almost got showered in gasoline, NO AIR came out.
I picked up a CPS, like i said, at the auto store on my way home. I replaced that. Started it up in the driveway, and let it run until it was warm. Seemed good. Thats no different from last night.
So i took it out for a ride, up the same strip that it stalled twice on me last night.
Made it all the way out, and back. No stalls.
So i took it down to fill up the gas tank, all went well.
So i took it out of town (nice sized hill). No problems.
back into town, the long way. No problems.
I drove about for a good half hour, uphills, downhills, up to 4th gear. Shut it off once while i was getting gas. No issues.
I dont dare say it's fixed, because then it'll break again, but i will say this.. It looks promising.
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By YJ Nate - 6/27/2010 11:27:58 AM
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jerreyjeep (6/26/2010)
on a side note: check/replace your fuel filter anyway. if ya ran the tank dry it coulda sucked some crap off the bottom of the tank.....same kinda thing happened to me on another vehicle...........drove me nuts untill I found the filter was my problem.
ps: my oil press is usually pegged while running!...jeep sensors are not reliable.
I bought the filter, just need to put it in.
Thanks for the suggestion.
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By YJ Nate - 7/23/2010 12:12:43 AM
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Thanks for the suggestions but... This issue is resolved.
See.
http://www.jeepaholics.com/support/FindPost661739.aspx
It was the Crank Position Sensor.
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By Al Bsharah - 6/23/2010 10:40:07 AM
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I had a mysterious engine dying issue years ago that turned out to be vapor lock. Release the valve on the fuel rail and tons of air spews out...then gas flows and you close it off. Fired right up for me. Then, well, the rig got stolen - so I'm not sure what the solution would have been for this...but that was certainly my issue.
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By Al Bsharah - 6/24/2010 6:43:20 AM
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Just so we're on the same page, so did mine. I had maybe 10-15 seconds of warning (sputter or two) before it cut out. Then, it was useless until the vapor was released (or a lot of time went by). Definitely happened on hotter days, though.
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