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Unread 05-02-2013, 09:43 PM   #1
neonhomer
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1996 ZJ 
 
Join Date: Sep 2010
Location: Edgewater, FL, Florida
Posts: 449
Weird stalling problem

This is kind of weird... but maybe I am overlooking something simple.

Driving the ole ZJ the other day with a female friend of mine, and it starts to cut out. Almost like it is misfiring. Sometimes you can just give it steady throttle, and it will clear up, and sometimes it will just die.

Now - here is where is gets weird. If you try to restart it, it won't restart. Turns over, but doesn't start. If you go under the hood, and bleed off the fuel rail (remove the test port cap and depress the schrader vale), then it will start back up, but no guarantee on how long it will stay running.\

Plugs are only a year old, along with the wires, cap, and rotor. O2 sensors are only a couple of months old (Mopar for the upstream, NTK for the downstream) Thought it might have been a vapor lock thing, so I replaced the fuel cap. Also, it doesn't matter if the tank is full or nearly empty. I've also tried different gas stations, thinking maybe I picked up a tank of bad gas. I had a P0351 (I think) code, so I have a new coil and will swap that out this weekend.

The only odd thing is when it is "missing", you can smell what smells like alcohol burning.

Any ideas? I can't drive the Jeep if I can't trust it.

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[COLOR="Lime"][SIZE="5"]NeonHomer[/SIZE][/COLOR]
Mid-Florida Jeep Club - Member
1996 Jeep Grand Cherokee, 4.0L/42RE/242 - Rebuilt motor w/ Comp cam (4/12), 3.5" Junkyard F>R lift, 31x10.5.x15 M/T's, Spartan Locked D44a, TC & tank skids, F&R adj trackbars, V8 steering arms
Galaxy DX99V CB, 102" SS Whip, Yaesu FT-2900R 2m, Larsen 1/4w mag mount, Sony HU, Massive 3way - F Door, Pioneer 3way - R Doors, MB Quart ONX304 Subs (x2), Lanzar 1600w amp.

"No Matter Where You Go... There You Are."
"Oh me oh my a lovely day is dawning. Oh what a joy I didn't wake up dead. So I can go to work and then resume my yawning, and get my sleep on site instead of in my bed" - Daria Morgendorffer (with my twist)
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Unread 05-03-2013, 06:59 AM   #2
Rich93ZJ
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1993 ZJ 
 
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Location: Richland, Ga
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When you "press the schrader valve" does the fuel come shooting out or is it more like a dribble. Throw a pressure gauge on there and report the readings. Sounds like the pump could be on its way out.
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Unread 05-03-2013, 12:09 PM   #3
Oldfrog
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1997 ZJ 
 
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http://www.jeepforum.com/forum/f13/i...l-fix-1487443/
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Words of wisdom, Posted by Zeejay:
"..it's not air, it is the opposite of air... suckage so to speak."

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Unread 05-04-2013, 05:52 PM   #4
neonhomer
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1996 ZJ 
 
Join Date: Sep 2010
Location: Edgewater, FL, Florida
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Checked fuel pressure. 50 PSI with the key on, engine off. With the engine running, the needle flutters between 42-50.

The code I had was a P0351 Ignition Circuit 1. I replaced the coil today with no luck.
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[COLOR="Lime"][SIZE="5"]NeonHomer[/SIZE][/COLOR]
Mid-Florida Jeep Club - Member
1996 Jeep Grand Cherokee, 4.0L/42RE/242 - Rebuilt motor w/ Comp cam (4/12), 3.5" Junkyard F>R lift, 31x10.5.x15 M/T's, Spartan Locked D44a, TC & tank skids, F&R adj trackbars, V8 steering arms
Galaxy DX99V CB, 102" SS Whip, Yaesu FT-2900R 2m, Larsen 1/4w mag mount, Sony HU, Massive 3way - F Door, Pioneer 3way - R Doors, MB Quart ONX304 Subs (x2), Lanzar 1600w amp.

"No Matter Where You Go... There You Are."
"Oh me oh my a lovely day is dawning. Oh what a joy I didn't wake up dead. So I can go to work and then resume my yawning, and get my sleep on site instead of in my bed" - Daria Morgendorffer (with my twist)
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Unread 05-04-2013, 10:30 PM   #5
dellis
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Following up on Rich's post, the PSI reading sounds good but the only way to tell if it is your pump is cutting out is to monitor the fuel PSI while you are driving ... like, running a hose from the fuel rail's Schrader valve to a gauge taped to your window.

I had a fuel pump that was going out. While driving, the fuel PSI would drop and the PCM significantly increased the fuel trim to compensate. Within 3-5 seconds the fuel pump would start up again with the high trim causing a temporary flooded condition in the engine (the "smell" you describe) - even got a few backfires (afterfires) through the cat/muffler. I supposed that the PCM interpreted this extremely rich condition as a spark problem, and it registered a P0351 code without a MIL illuminated.
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Unread 05-05-2013, 08:13 AM   #6
Oldfrog
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P0351 is a common code thrown when the PCM is bad or the PCM connectors are not making good contact. Electrical grounding points need cleaning at battery, fender well, below oil dipstick, and at the coil. Clean each of the fuse and relay contact surfaces in the PDC ( fuse box under the hood), as well as the battery connections on the side of the PDC.

This issue is a biotch to track down and you may go through 3 or 4 new PCMs before it's solved. ( I'm on my 4th).

To test my theory, start the engine ( if it WILL start), let it idle...and wiggle the PCM connectors. If it dies or tries to stall......you're on the right track.
__________________
Cajun Recipes and Fishing tips

Words of wisdom, Posted by Zeejay:
"..it's not air, it is the opposite of air... suckage so to speak."

Stalling? Work through Zeejay's list
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Unread 05-06-2013, 05:17 PM   #7
neonhomer
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Join Date: Sep 2010
Location: Edgewater, FL, Florida
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Quote:
Originally Posted by Oldfrog View Post
P0351 is a common code thrown when the PCM is bad or the PCM connectors are not making good contact. Electrical grounding points need cleaning at battery, fender well, below oil dipstick, and at the coil. Clean each of the fuse and relay contact surfaces in the PDC ( fuse box under the hood), as well as the battery connections on the side of the PDC.

This issue is a biotch to track down and you may go through 3 or 4 new PCMs before it's solved. ( I'm on my 4th).

To test my theory, start the engine ( if it WILL start), let it idle...and wiggle the PCM connectors. If it dies or tries to stall......you're on the right track.
It will start when cold. I fired it up, let it warm up, and while it was warming up, proceeded to start with the wiggle test, checking all of the connectors from the PCM back. Nothing....

One thing I noticed, and it might have been a fluke. When it died the other night, I tried to restart it while rolling. It wouldn't start. For some reason (and I blame old Volkswagens for this), I turned the key to Off, and then back on to restart it. It fired right up.
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[COLOR="Lime"][SIZE="5"]NeonHomer[/SIZE][/COLOR]
Mid-Florida Jeep Club - Member
1996 Jeep Grand Cherokee, 4.0L/42RE/242 - Rebuilt motor w/ Comp cam (4/12), 3.5" Junkyard F>R lift, 31x10.5.x15 M/T's, Spartan Locked D44a, TC & tank skids, F&R adj trackbars, V8 steering arms
Galaxy DX99V CB, 102" SS Whip, Yaesu FT-2900R 2m, Larsen 1/4w mag mount, Sony HU, Massive 3way - F Door, Pioneer 3way - R Doors, MB Quart ONX304 Subs (x2), Lanzar 1600w amp.

"No Matter Where You Go... There You Are."
"Oh me oh my a lovely day is dawning. Oh what a joy I didn't wake up dead. So I can go to work and then resume my yawning, and get my sleep on site instead of in my bed" - Daria Morgendorffer (with my twist)
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Unread 05-06-2013, 08:20 PM   #8
Rich93ZJ
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Could also be your crank sensor. Those little bastards will play all kinds of Jedi mind tricks on you. Here is a great video on how to test it. http://www.jeepforum.com/forum/f13/g...ensor-1516624/
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Unread 05-07-2013, 06:10 PM   #9
neonhomer
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Crank sensor was replaced last year with a new Mopar one when I was troubleshooting a no-start condition. (Turned out to be a bad rotor button.)
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[COLOR="Lime"][SIZE="5"]NeonHomer[/SIZE][/COLOR]
Mid-Florida Jeep Club - Member
1996 Jeep Grand Cherokee, 4.0L/42RE/242 - Rebuilt motor w/ Comp cam (4/12), 3.5" Junkyard F>R lift, 31x10.5.x15 M/T's, Spartan Locked D44a, TC & tank skids, F&R adj trackbars, V8 steering arms
Galaxy DX99V CB, 102" SS Whip, Yaesu FT-2900R 2m, Larsen 1/4w mag mount, Sony HU, Massive 3way - F Door, Pioneer 3way - R Doors, MB Quart ONX304 Subs (x2), Lanzar 1600w amp.

"No Matter Where You Go... There You Are."
"Oh me oh my a lovely day is dawning. Oh what a joy I didn't wake up dead. So I can go to work and then resume my yawning, and get my sleep on site instead of in my bed" - Daria Morgendorffer (with my twist)
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Unread 05-26-2013, 06:04 PM   #10
neonhomer
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Okay... Here is a new bit to add... Driving down the road, all is good... until the motor starts stumbling, and eventually dies. If you turn the key off, wait 5-10 seconds, and then restart it, it will fire back up (after a little cranking).

Almost like the ignition is just dropping out..
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[COLOR="Lime"][SIZE="5"]NeonHomer[/SIZE][/COLOR]
Mid-Florida Jeep Club - Member
1996 Jeep Grand Cherokee, 4.0L/42RE/242 - Rebuilt motor w/ Comp cam (4/12), 3.5" Junkyard F>R lift, 31x10.5.x15 M/T's, Spartan Locked D44a, TC & tank skids, F&R adj trackbars, V8 steering arms
Galaxy DX99V CB, 102" SS Whip, Yaesu FT-2900R 2m, Larsen 1/4w mag mount, Sony HU, Massive 3way - F Door, Pioneer 3way - R Doors, MB Quart ONX304 Subs (x2), Lanzar 1600w amp.

"No Matter Where You Go... There You Are."
"Oh me oh my a lovely day is dawning. Oh what a joy I didn't wake up dead. So I can go to work and then resume my yawning, and get my sleep on site instead of in my bed" - Daria Morgendorffer (with my twist)
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Unread 05-26-2013, 06:24 PM   #11
Rich93ZJ
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Still sounds like the crank sensor or pcm connections. Have you tried the trick on the male end of the plug where you spread open the pins to make a better connection?
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Unread 05-26-2013, 07:16 PM   #12
neonhomer
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Spread open or pinch closed? Not yet. I'm trying to eliminate other possibilities before playing with the PCM connections. I try to wiggle the connectors, and nothing happens.

A lot of posts I've seen about bad connectors is that the Jeep won't start. Mine starts fine. It just decided to die out. If you drive it for a short trip, it's fine. Drive it longer that 20 minutes or so is when the problems start. The only code I end up with is the one about Ignition Circuit 1.

I'm having trouble believing its a crank sensor as this sensor is a Mopar sensor, not a parts house knock off. Anything is possible I suppose, but I'm still having trouble believing it.
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[COLOR="Lime"][SIZE="5"]NeonHomer[/SIZE][/COLOR]
Mid-Florida Jeep Club - Member
1996 Jeep Grand Cherokee, 4.0L/42RE/242 - Rebuilt motor w/ Comp cam (4/12), 3.5" Junkyard F>R lift, 31x10.5.x15 M/T's, Spartan Locked D44a, TC & tank skids, F&R adj trackbars, V8 steering arms
Galaxy DX99V CB, 102" SS Whip, Yaesu FT-2900R 2m, Larsen 1/4w mag mount, Sony HU, Massive 3way - F Door, Pioneer 3way - R Doors, MB Quart ONX304 Subs (x2), Lanzar 1600w amp.

"No Matter Where You Go... There You Are."
"Oh me oh my a lovely day is dawning. Oh what a joy I didn't wake up dead. So I can go to work and then resume my yawning, and get my sleep on site instead of in my bed" - Daria Morgendorffer (with my twist)
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Unread 05-26-2013, 07:23 PM   #13
Rich93ZJ
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Location: Richland, Ga
Posts: 454
I hear ya. It shouldn't die in a year but it sure sounds like it. Try the pcm trick and see what happens. Could also try swapping the ASD relay with another from the bank. Also, check for chafed wires (CPS and O2). Thats all I can think of atm. Oh yea, one more thing. Is it low on trans fluid?
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Unread 05-27-2013, 11:25 AM   #14
neonhomer
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Location: Edgewater, FL, Florida
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It's not low on tranny fluid. I keep that in check. I will try the relay thing. I have a few spare relays laying about.

Will check the wires as well. I know I had a downstream O2 sensor wiring that was rubbing on the output of the transfer case. That caused the PCM fuse to pop. I fixed that a year or so ago, by soldering and heatshrinking a new connector and pigtail on to the Jeep end of the harness. (BTW - Both O2 sensors are new NTK parts.)

I might have to break down and find one of my picks and start at the PCM harness.
__________________
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[COLOR="Lime"][SIZE="5"]NeonHomer[/SIZE][/COLOR]
Mid-Florida Jeep Club - Member
1996 Jeep Grand Cherokee, 4.0L/42RE/242 - Rebuilt motor w/ Comp cam (4/12), 3.5" Junkyard F>R lift, 31x10.5.x15 M/T's, Spartan Locked D44a, TC & tank skids, F&R adj trackbars, V8 steering arms
Galaxy DX99V CB, 102" SS Whip, Yaesu FT-2900R 2m, Larsen 1/4w mag mount, Sony HU, Massive 3way - F Door, Pioneer 3way - R Doors, MB Quart ONX304 Subs (x2), Lanzar 1600w amp.

"No Matter Where You Go... There You Are."
"Oh me oh my a lovely day is dawning. Oh what a joy I didn't wake up dead. So I can go to work and then resume my yawning, and get my sleep on site instead of in my bed" - Daria Morgendorffer (with my twist)
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Unread 05-27-2013, 01:34 PM   #15
Oldfrog
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1997 ZJ 
 
Join Date: Feb 2008
Location: Louisiana/Texas
Posts: 3,821
Another tidbit...Read this carefully.

http://dodgeram.info/tsb/1997/08-01-97.htm
__________________
Cajun Recipes and Fishing tips

Words of wisdom, Posted by Zeejay:
"..it's not air, it is the opposite of air... suckage so to speak."

Stalling? Work through Zeejay's list
Oldfrog is online now   Reply With Quote




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