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Hey all, I have an '87 4.0L I6 4x4 and while driving along it will just shut off like the key has been turned off. Fuel is getting to the rails (you can smell fuel if you keep trying to start it long enough) and there is spark from the distributor. The starter keeps cranking the engine but the engine never catches. I replaced the lock cylinder since it also had a problem and it still does this. It is a big problem because I do not even want to drive the vehicle anywhere because I might end up stranded on the road with my only recovery options being AAA or waiting and continually trying to start it.
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When you replaced the lock cyl.,did you set-up the ignition switch?Have you looked for any loose wires from the ignition or on the coil?
DennisDennis and Tammy
Its as much fun getting dirty as it is being dirty in a Jeep! -
[COLOR="Sienna"]If there is fuel getting to the cylinder and spark also, the only things missing are air and compression. This could be caused by several things, have you done a compression test?[/COLOR][COLOR="darkred"]"Death Smiles at Everyone... Marines Smile Back."
Adopt-a-Trail Member.[/COLOR]Comment
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This kind of problem is commonly caused by the CPS (crankshaft position sensor) going bad. The CPS picks up timing information off the flywheel and provides the engine's master timing signal so when it goes bad, the engine will die. You can find the CPS up high on the driver's side where the transmission bolts to the block. An engine that won't start from a bad CPS can often be temporarily coaxed to start by disconnecting/reconnecting the CPS connector that is up by the firewall.The Geezer Jeep: http://www.greentractortalk.com/jerryb/index.htmComment
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100% correct,... I was going to post that as well Jerry. A 70 dollar part that will give you tons of grief till replaced. I had it happen to me a few years ago. If facing the front of the vehicle its about 2 o'clock right where jerry said it is. Hope that fixes it for you. Most likely that's it. And even if it is not you want to carry one around in your toolbox anyway trust me.Originally posted by Jerry Bransford View PostLast edited by Matt2001TJ; 10-31-09, 01:07 PM."Just Another Jeepin Guy"Comment
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I see you moved the thread. Here was my post above.
A quick check will show. But, it's usually 4 things. Air, fuel, Spark (CPS also), and compression.
Good luck. Hope you get it fixed...AND Welcome!
http://www.automedia.com/Engine_Comp...cr20050801cc/2
The key point here is that an engine with low sealing compression in one or more cylinders will never run right—no matter how many new parts are connected to it.
http://yotatech.com/f116/engine-cran...hanics-194573/
Spark, fuel, air, and compression
http://www.tpub.com/engine2/en2-74.htm
ENGINE STALLS FREQUENTLY OR STOPS SUDDENLY
LOSS OF COMPRESSION.–A cylinder may misfire due to loss of compression, which may be caused by a leaking cylinder head gasket, leaking or sticking cylinder valves, worn pistons, liners or rings, or a cracked cylinder head or blockComment
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Geez Ron it was in the other thread...
Quote:
Originally Posted by Jeep4cern View Post
What year is it? Have you done a compression check with 414k miles.
ZexGx'87. It's had two rebuilds and I'm pretty sure on the last rebuild a mild cam was installed. Other than randomly cutting out it runs and drives just fine, until it shuts off. Doesn't seem like something that compression loss would cause. Like I said, the starter just keeps cranking the engine and it just never catches.
I made a post in the Tech section regarding this problem: http://www.myjeeprocks.com/forums/sh...ewpost&t=15770
Last edited by ZexGX; 10-30-09 at 08:12 PM.
Are all your grounds clean?An XJ will always cost you less then any girl ever will, and you will always know when the spark is gone.Comment
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Sean,Originally posted by 2blk2drs View Post
I highlighted his reply (as you did). My reply was moved here as his topic was relocated here. Second, the links were posted to show that poor compression can cause those issues.
Let's be frank, 414k miles on any car is a lot. He stated two rebuilds, But, did he say at what mileage? Nope. So, at 414k maybe the last rebuild was done at 250k. Ummm, that might be the issue.
If you felt better attacking me for helping him, I am glad that I helped you also.Last edited by Jeep4cern; 11-07-09, 09:07 AM.Comment
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I'm wondering if it may be something as simple as a fuel filter. He says he has spark, and if the cps was bad, it wouldn't send a signal to the dist. so would he still have spark? The gentleman states that he has fuel to the rail, but has he put a pressure gauge to it to see how much pressure he's getting? No doubt that it something silly and simple. But you need to start at the beginning and start eliminating. If it can make it to Hesperia, one of these weekends, I be happy to take a look at it, Kevin. 760-220-7113Comment
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I had the same problem in 87' XJ over 10 years ago I remember changing the CPS and that fixed the problem.You can lead a horse to water, but it might drownComment
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The last rebuild was around 65k miles ago I believe. I myself don't trust it to make it around the block, but I'm sure it could. haha. I need to get a pressure gauge on the rail and if that checks out, try replacing the CPS. I took a quick look under the hood to try and locate the CPS but it wasn't obvious, so I'll have to check one of the service manuals I have for it.
Spark is iffy. My dad's way of thinking he can get it to run is to loosen the distributor wire and let it rest on the connection (rather than being clipped on) then try to start the car. Then he says when the car starts (only sometimes) he uses something non-conductive to push the connector back on the distributor. I don't know why he thinks making the connection loose and having it arc would make it work. He did replace the distributor and the problem remained. I am liking the CPS idea because it sounds like my issue.
The reason I say it doesn't seem like a compression issue is because it starts and runs and drives just fine. Then as you're driving along it can just shut off and turn over but won't start. If it was a compression issue shouldn't I be noticing a huge loss of power, misfires, or any other issues? Other than the shutting off and not starting again, it doesn't have a lopey idle, misfires, or anything like that. It sounds and feels great just until it dies.
The grounds look fine to me - there is no corrosion or rust. There are quite a few lines grounded to the same ground in the PDC area though.Last edited by ZexGX; 11-12-09, 04:09 PM.Comment
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I wonder if it's my old Jeep... sound exactly like what was going on with mine.... CPSYou can lead a horse to water, but it might drownComment
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To locate the cps: Open the hood, and face the jeep dead on (crank pointing at your nuts) Look at the back of the intake manifold, and there will be a plug coming up from the back of the trans. follow that wire to a sensor mounted on top of the trans tunnel. Be Very careful not to drop the two small bolts down the trans. Go ahead, ask me how i know....
And Ron: sorry bro shoulda put a smiley in there for ya. :beer: better late than never :beer:An XJ will always cost you less then any girl ever will, and you will always know when the spark is gone.Comment
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Sean...:beer::beer:
My old Ford F250 shut off once or twice. The CPS was bad. Dealer recall.
Does it loose oil? If so, rings could be bad. Low compression then. One sign I guess.
Disconnect the sensor (cps). if you notice no difference, its bad
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ill bet money on it,...thats it.Originally posted by Toolman View Post"Just Another Jeepin Guy"Comment
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