post #91 of Old 05-01-2013, 05:40 PM
ijusgottajeep
Registered User
1994 ZJ 
 
Join Date: Apr 2013
Location: Naples
Posts: 8
http://www.parts-express.com/pe/show...umber=020-1746
heres the better deal on capacitors. 43 cents a pop plus shipping but they are rated for 220 degrees/ 105 c

ijusgottajeep is offline  
post #92 of Old 08-02-2013, 10:41 AM
diamondflaw
Registered User
1993 ZJ 
 
Join Date: Mar 2013
Location: Ponderay
Posts: 20
Another happy camper here thanks to this post! Just finished this last night, and I am ecstatic! I think other people have said this, but the caps will not necessarily look domed, mine didn't (definitely looked sad, but not domed).

Over last couple of months my '93 4.0 had steadily needed more and more delay and cranks to start until about 4 days ago it just wouldn't start anymore, noticed CEL not tripping when turned to "on" and found this post.

After replacing these, no more need to wait before starting, starts on the first crank, and (could be my imagination just 'cause I'm excited to have her running again) the throttle seems more responsive on the road.

THANK YOU!
diamondflaw is offline  
post #93 of Old 09-07-2013, 04:38 PM
stretchallen25
Registered User
1994 ZJ 
 
Join Date: Aug 2012
Location: Yerington
Posts: 34
Hi guys, I am new to this forum but I have read many threads about multiple things regarding stalling, dying, rough idles and have been searching endlessly trying to find a good relation to what my problem is. I have a 1994 Jeep Grand Cherokee V8 5.2L and I think it is a ZJ from doing some research. I am so frustrated with this issue. I have replaced fuel pump, fuel filter, did complete tune-up about 3 months ago. The problem is somewhat similar to others. I usually have no issues starting it when its cold only when it gets to normal temperature and then it usually starts my problem. My voltage starts out normal but as it warms up it slowly goes down while driving to around 12 volts. And when warm if I turn it off and then try to start it again, the volts will be low and it idles low and kinda rough and if I try to put it into reverse, it sometimes will die or at least, the RPMs will go really low and almost dies. Now this is only happening when it is warmed up. New battery in it also. Took it to get it tested at Autozone and battery passed, but he said my voltage regulator failed and I think he said diodes passed also. So I then asked him if the voltage regulator could just be replaced and he told me no that it was internally in the Alternator so I thought it was in the PCM. So I did buy the new alternator but it changed absolutley nothing so I took it back out and took it back for a refund. So if anybody can help me with this confirming that I need to replace my PCM. so as my jeep warms up, the problem starts so is the PCM getting too hot? Or could it be the IAC? Please help as I have 4 kids that I have to take back and forth to school everyday. Thanks a lot and I appreciate it very much.
stretchallen25 is offline  
post #94 of Old 09-07-2013, 06:48 PM
NJ2MDJim
Registered User
1993 ZJ 
 
Join Date: Aug 2010
Location: North East, Md
Posts: 53
Very thorough write-up and clear pictures. I believe you have helped a lot of people today by showing them that they can do this themselves.
NJ2MDJim is offline  
post #95 of Old 09-08-2013, 12:34 AM
moggie99
Registered User
1996 ZJ 
 
Join Date: Sep 2011
Location: Al Ain
Posts: 680
Thank you to everyone who has contributed to this thread. I have just ordered the high temperature capacitors from partsexpress to tackle this job on my 1995 Cherokee which has a habit of cutting out in the desert (but which always restarts once cooled down a bit)

A thought: if, as it seems, the problem is that the PCM fails to power up the fuel pump, could we not just run a manually switched 12v supply to the pump?

Richard Moss
'96 ZJ 4L auto, '95 XJ 4L manual, 2000 Nissan Patrol Y61
In the UK: 1969 MGC GT
moggie99 is offline  
post #96 of Old 10-06-2013, 12:42 PM
Rimfired
Registered User
1993 ZJ 
 
Join Date: Jul 2013
Location: Oxnard
Posts: 30
Thanks for the writeup, I just fixed my pcm yesterday and confirmed a good fix this morning. At first I thought it was a bad check valve in the fuel pump assembly, but slowly the time it took from turning the key to on, the check engine light coming on and the fuel pump priming got longer and longer, and that confirmed the diagnosis of a "lazy pcm". This morning the check engine light came on immediately, the fuel pump primed immediately and the Jeep started right up.

As a tip, I got the high temp caps from Fry's Electronics, so if anyone has a store locally, that's the place to get them.
Rimfired is offline  
post #97 of Old 10-06-2013, 02:41 PM
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Posts: 8,550
Quote:
Originally Posted by moggie99 View Post
A thought: if, as it seems, the problem is that the PCM fails to power up the fuel pump, could we not just run a manually switched 12v supply to the pump?
PCM does not power the pump. the pcm supplies a ground to the fuel pump relay. i would never suggest that the fuel pump be manually operated, foremost for safety (auto shutdown is engineered safety) with practicality running a close second (forget to turn it off)
ZeeJay1997 is offline  
post #98 of Old 10-07-2013, 05:31 AM
moggie99
Registered User
1996 ZJ 
 
Join Date: Sep 2011
Location: Al Ain
Posts: 680
I did the capacitor swap but am still getting the cutting out at high temperatures. I shall bite the bullet and buy a remanufactured PCM and a new CPS and (hopefully) that will cure the issue. I can't afford to have the car keep cutting out on me out in the desert.

Richard Moss
'96 ZJ 4L auto, '95 XJ 4L manual, 2000 Nissan Patrol Y61
In the UK: 1969 MGC GT
moggie99 is offline  
post #99 of Old 10-07-2013, 05:08 PM
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Posts: 8,550
Quote:
Originally Posted by moggie99 View Post
I did the capacitor swap but am still getting the cutting out at high temperatures. I shall bite the bullet and buy a remanufactured PCM and a new CPS and (hopefully) that will cure the issue. I can't afford to have the car keep cutting out on me out in the desert.
define cutting out. is it a miss or does it shut off and wont start until it cools off?
ZeeJay1997 is offline  
post #100 of Old 10-08-2013, 12:43 PM
Tony
Registered User
1995 ZJ 
 
Join Date: Apr 2001
Location: Georgia
Posts: 22
Quote:
Originally Posted by moggie99 View Post
I did the capacitor swap but am still getting the cutting out at high temperatures. I shall bite the bullet and buy a remanufactured PCM and a new CPS and (hopefully) that will cure the issue. I can't afford to have the car keep cutting out on me out in the desert.
Keep us posted if you find the problem. My '95 does the same thing, runs great then just suddenly dies as if the ignition had been turned off, no hesitating or miss, just dies and will not start. Once it cools down it will start on the first try and runs great again, but I never know when it will randomly quit.

1995 & 2007 Grand Cherokees
Tony is offline  
post #101 of Old 10-09-2013, 02:58 PM
moggie99
Registered User
1996 ZJ 
 
Join Date: Sep 2011
Location: Al Ain
Posts: 680
Quote:
Originally Posted by ZeeJay1997 View Post
define cutting out. is it a miss or does it shut off and wont start until it cools off?
The latter - it shuts down and I have to cool the PCM with ice cubes from my cool box and then it will start and run OK. It only happens when off-road due to the higher underbonnet temperatures from high power/low speed running, on road is fine (as are the stretches of off-road where I can crank up the speed).

I've bought a load of wire and solder and plan to extend the PCM wiring loom to bring it inside the car (which is MUCH cooler than the engine bay) and add a PC cooling fan to the box.

Richard Moss
'96 ZJ 4L auto, '95 XJ 4L manual, 2000 Nissan Patrol Y61
In the UK: 1969 MGC GT
moggie99 is offline  
post #102 of Old 10-09-2013, 05:52 PM
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Posts: 8,550
Quote:
Originally Posted by moggie99 View Post
The latter - it shuts down and I have to cool the PCM with ice cubes from my cool box and then it will start and run OK. It only happens when off-road due to the higher underbonnet temperatures from high power/low speed running, on road is fine (as are the stretches of off-road where I can crank up the speed).
It may be the crank sensor. when it does it again, pull the connector from the TPS and check the outside contacts for 5v. sometimes the crank sensor shorts sensor reference circuit in PCM. you're measuring at the tps because it is on the same circuit and is easiest to access for testing.
ZeeJay1997 is offline  
post #103 of Old 10-10-2013, 12:28 AM
moggie99
Registered User
1996 ZJ 
 
Join Date: Sep 2011
Location: Al Ain
Posts: 680
Quote:
Originally Posted by ZeeJay1997 View Post
It may be the crank sensor. when it does it again, pull the connector from the TPS and check the outside contacts for 5v. sometimes the crank sensor shorts sensor reference circuit in PCM. you're measuring at the tps because it is on the same circuit and is easiest to access for testing.
Thanks - I already have a new CPS on order and will be changing it on a "just in case" basis.

Richard Moss
'96 ZJ 4L auto, '95 XJ 4L manual, 2000 Nissan Patrol Y61
In the UK: 1969 MGC GT
moggie99 is offline  
post #104 of Old 10-30-2013, 10:49 AM
Tony
Registered User
1995 ZJ 
 
Join Date: Apr 2001
Location: Georgia
Posts: 22
Just an FYI, I posted that I was having a similar problem earlier. I replaced the CPS and no more cutting off or no starts for almost 2 weeks. Seems to have been the CPS.

1995 & 2007 Grand Cherokees
Tony is offline  
post #105 of Old 11-07-2013, 12:26 AM
moggie99
Registered User
1996 ZJ 
 
Join Date: Sep 2011
Location: Al Ain
Posts: 680
I replaced the CPS about 2 weeks ago - no cutting out since. It has only had one offroad trip in the desert but it performed perfectly. Another guy in the group did have his XJ cut out a few times but throwing cold water on the CPS got him going again.

When mine was playing up before, what was noticeable before was that just before cutting out it would lose power, but no problems this time. Fingers crossed that this is fixed now.

Richard Moss
'96 ZJ 4L auto, '95 XJ 4L manual, 2000 Nissan Patrol Y61
In the UK: 1969 MGC GT
moggie99 is offline  
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
Lazy WJ?? GrandHokie96 ZJ Grand Cherokee Forum 6 07-26-2009 08:09 PM
99 GC Limited Lazy Shift to 3rd. Islesfan079 ZJ Grand Cherokee Forum 1 07-05-2009 09:40 PM
Lazy PCM, Capacitor replacement how-to? Steve Bohnen ZJ Grand Cherokee Forum 6 01-01-2008 10:27 AM
Lazy mirror!?! froggo27 ZJ Grand Cherokee Forum 4 05-31-2007 04:50 PM
lazy quadradrive trek96 WJ Grand Cherokee Forum 1 11-01-2003 06:18 AM

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome