So i have a 90 XJ 6cyl. I went out friday to start it after sittin for a few days and it took awhile to fire up, now after a few more days it wont start at all. Its got fuel and the lines and filter are clean, i pulled a plug wire and there is no spark, so im thinking its the ignition box.Any ideas???????????
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Cranks but wont start
- Thread starter Gray XJ
- Start date
- Location
- Westminster, SoCal
Gray XJ said:
CPS?
SouthernXJ
NAXJA Forum User
- Location
- South Carolina
What would be nice is if someone made a sticky with the most common XJ problems and the common cuplprits. Not that there are too many people asking questions, but a model specific FAQ is always a good idea. Who's up for that chore?
Hawaiian Style
NAXJA Forum User
- Location
- JAX
:roflmao:
No I've got a better idea. Let's make sure that everyone who comes to this site gets this information right away...
:jester:
No I've got a better idea. Let's make sure that everyone who comes to this site gets this information right away...
:jester:
- Location
- Westminster, SoCal
SouthernXJ said:
If someone comes up with a nice article and sends it to [email protected] I'm pretty sure it will end up in the tech section
Hawaiian Style
NAXJA Forum User
- Location
- JAX
OK, instead of being a smart ass maybe I could write something up... Give me a day.
Hawaiian Style
NAXJA Forum User
- Location
- JAX
Gray,
It could be a whole bunch of things but 99.9% of the no spark problems seen here are CPS related. The CPS tells the ECU or PCU computer where top dead center is by sensing the gear teeth on the fly wheel. If the sensor is failing or failed your XJ won't start or it might sometimes start and have interminent stalling, surging, fast idle, ect. It's a 20-40 dollar part that you can buy at just about any autoparts store or dealership. Not a huge job to replace either. Pretty quick and easy. Lot's of writeups here on the boards on how to do the job.
It could be a whole bunch of things but 99.9% of the no spark problems seen here are CPS related. The CPS tells the ECU or PCU computer where top dead center is by sensing the gear teeth on the fly wheel. If the sensor is failing or failed your XJ won't start or it might sometimes start and have interminent stalling, surging, fast idle, ect. It's a 20-40 dollar part that you can buy at just about any autoparts store or dealership. Not a huge job to replace either. Pretty quick and easy. Lot's of writeups here on the boards on how to do the job.
Greg Smith
Jeep addict
- Location
- Spotsylvania, Virginia
A crank no start and no spark is usually the cps (crank position sensor) as stated above. Note a bad cps can also cause rough running, missing etc. This is especially true of pre 91s. Here are some posts I have made in the past on how to replace the cps and how to rebuild the cps wire harness connector.
First unplug and replug the cps wire harness connector this usually establishes a better connection and should get you going. It not use a volt meter and disco the cps and crank engine and note voltage output from cps. It should generate .5 to .8 or more volts. If not replace it. If it does rebuild the connector espcially on female wire harness side.
Replacing the cps:
Replacement is as follows on 4.0 w. automatic (a little harder on a manual tranny from what I hear). I got it down to 30 minutes on my 89 4.0 auto. Here is how I do it. 3/8 inch ratch attached to 2 to 3 8 to 10 inch extentions w. a universal joint then a 2-3 inch extention attached to a 11 mm (IIRC) socket w. a 3/8 inch drive ratchet. A light is a must. I come at the bolts from underneath the car but from up high in the tranny tunnel coming as straight at the bolts as possible. Remove top bolt first and replace it last to avoid droping it into the cps hole in the bellhousing. Start all bolts in by hand first to avoid cross threading ( can use socket on extension in your hand to do this but by hand to control feel to avoid cross threading). I did this once in 25 minutes on the street in the dark w. a flash light. However I have now determined that most cps problems espcially on the pre 91s are due to a bad cps wire harness connector, IMHO.
Rebuilding the wire harness connector:
If on a crank but no start the unplug and replug of the cps wire harness connector gets you going you may just have a wire harness connector going bad and may not need to replace the cps sensor. Here is how to test: hook volt meter to both wires from cps sensor w. harness unplugged. Set the range on meter to less than one volt. Crank engine and if cps generates .5 to .8 or more volts it is ok and your connectors need tightening or replacing. I got my parts for a couple of $ at pepboy but advanceauto.com also has them. They were made my Dorman under the Motormite Conductite tech grad name # 85303, 85304 and 85305. There are about 5 pieces in each box. You can also get a small tool set that helps on the install number 85360. I fixed my 89 this way a couple of months ago when I got tired of unplugging and replugging the connector every few weeks. My cps was only 1 yr old so the engine side harness connector part was worn out. I replaced both the female and male side internals of the connectors and it not only starts every time but the idle was also improved.
Greg
First unplug and replug the cps wire harness connector this usually establishes a better connection and should get you going. It not use a volt meter and disco the cps and crank engine and note voltage output from cps. It should generate .5 to .8 or more volts. If not replace it. If it does rebuild the connector espcially on female wire harness side.
Replacing the cps:
Replacement is as follows on 4.0 w. automatic (a little harder on a manual tranny from what I hear). I got it down to 30 minutes on my 89 4.0 auto. Here is how I do it. 3/8 inch ratch attached to 2 to 3 8 to 10 inch extentions w. a universal joint then a 2-3 inch extention attached to a 11 mm (IIRC) socket w. a 3/8 inch drive ratchet. A light is a must. I come at the bolts from underneath the car but from up high in the tranny tunnel coming as straight at the bolts as possible. Remove top bolt first and replace it last to avoid droping it into the cps hole in the bellhousing. Start all bolts in by hand first to avoid cross threading ( can use socket on extension in your hand to do this but by hand to control feel to avoid cross threading). I did this once in 25 minutes on the street in the dark w. a flash light. However I have now determined that most cps problems espcially on the pre 91s are due to a bad cps wire harness connector, IMHO.
Rebuilding the wire harness connector:
If on a crank but no start the unplug and replug of the cps wire harness connector gets you going you may just have a wire harness connector going bad and may not need to replace the cps sensor. Here is how to test: hook volt meter to both wires from cps sensor w. harness unplugged. Set the range on meter to less than one volt. Crank engine and if cps generates .5 to .8 or more volts it is ok and your connectors need tightening or replacing. I got my parts for a couple of $ at pepboy but advanceauto.com also has them. They were made my Dorman under the Motormite Conductite tech grad name # 85303, 85304 and 85305. There are about 5 pieces in each box. You can also get a small tool set that helps on the install number 85360. I fixed my 89 this way a couple of months ago when I got tired of unplugging and replugging the connector every few weeks. My cps was only 1 yr old so the engine side harness connector part was worn out. I replaced both the female and male side internals of the connectors and it not only starts every time but the idle was also improved.
Greg
I'm no tech peson by any means but I have had an ongoing starting problem for 6 years with my 95. I have replaced CPS and wires and plugs and lots of other stuff. I just replaced my coil and found it was cracked on the bottom where I couldn't see it. I hope that fixed it. I have taken it to two Jeep dealers and two independent shops and no one could fix it. Its worth a look and it may save you the several hundred buck I spent looking for the problem.
Steve
Steve
