cherokee won't start

[85zebracherokee]

I have a 90 cherokee 4.0 5 speed, my problem is it won't start. It turns over but won't start, all the connections are like they should be that I can think of.I checked the coil I tried to ground it out to the block and check for a spark but there wasn't any. could it need a new coil? The thing is it's done it before, it'll run fine for a while like a week then it won't start for an hour up to a week.I'm all out of ideas please help!!!!!!!!!!!!!!!!!!!!!
On the plus side I just got a 3" lift and 31s on it and it was fun until it wouldn't start.
I need help I need some ideas to work with.

[ROGLSTUBB]

Look in the manual for the resistance values for the primary and secondary coils inside the coil itself. This should tell you if your coil is bad. If your not confindent with this autozone will check some for free. Did you try pulling your codes? I recommend you start simple work your way to the more complex.

[XJNick]

Hi,

I could be worng but I believe the '90 cherokees used the same Bendix/Renix Fenix II (try saying that really fast 5 times ) computer system. This system was definately used in the 1989 and previous years and does NOT generate or store any trouble codes. The only diagnostics this system provides is "live" monitoring of the system while the engine is running.

-Nick

[bremery88]

Sounds like a Camshaft Positioning sensor.....

http://www.jeepz.com/index.php?name=...9e62e9266cac2d

Look for my post....

I let mine sit for about an week and it would not start. Next day it started right up. This is worth a shot.

[Sound_Man]

Here is a write up I did a long time ago. http://www.jeepz.com/index.php?name=...672&highlight= It really does sound like it is the CPS. I carry a spare in the glove box now. If that thing dies the jeep becomes a heep and will not move on it's own power.

~Curt

	Crank position sensor A crank sensor is a component used in an internal combustion engine to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control ignition system timing and other engine parameters. Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on the engine.

[85zebracherokee]

it was the cam posistion sensor I looked at some other web sites and they said the same thing. So how do you fix the problem? Get a new sensor or tightet the bolts? All I know is its a pain to get to.

[bremery88]

mostly its the connector that fails. I have heard of people soldering the wires, but you can get a new sensor for about $50. To install there are two bolts that need to be pulled out that are on the bell housing (drivers side). I used a series of extensions and universal joints to get to them. You also might need to adjust the sensor, I am not sure how to do this, I had it done for me.

[Sound_Man]

Originally Posted by 85zebracherokee

So how do you fix the problem?

http://www.jeepz.com/index.php?name=...672&highlight=

[XJNick]

Hi,

just want to clear something up: There are two sensors brought up in this thread, the Camshaft Position Sensor and the Crankshaft Position Sensor. They are NOT the same thing.

The Camshaft Postion Sensor is located in the base of the distributor, and provides little reference to the computer, except camshaft location as read by the position of the distributor.

The Crankshaft Position Sensor (CPS) is located towards the driver's side top of the transmission bellhousing, and provides very important information to the computer such as engine RPMs, Top Dead Center (TDC) location, etc.... Thus it is this sensor which usually causes no start conditions or erratic engine operation when it fails.

So, although both sensors could be abbrieviated CPS, it usually refers to the Crankshaft Position Sensor

-Nick

	Crank position sensor A crank sensor is a component used in an internal combustion engine to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control ignition system timing and other engine parameters. Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on the engine.

[Bounty__Hunter]

Get it fixed yet? Is it getting fuel? Do you hear the fuel pump running when the key is turned to run?

[85zebracherokee]

I meant crank sensor, and it runs fine, when it doesn't start i just tap on it with a piece of pipe or something and it starts. I need to fix the problem, but i'm procrastinating even though my brother works at O'reillys.
Thanks for the help.

	Crank position sensor A crank sensor is a component used in an internal combustion engine to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control ignition system timing and other engine parameters. Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on the engine.

[Sound_Man]

I was able to do the same thing with mine. I am willing to bet that you have some other stuff going on.

Mine was doing the exact same thing. The CPS was getting metal fillings on it (it is a magnetic sensor). They were from the starter gear going bad and flipping around from the flywheel and sticking to the sensor. If I smacked it real good with anything I could get up in there it would drop or move the metal around enough that the sensor would work for a little bit. Eventually it quit and I replaced the sensor. I went for about a day before it started again. Pulled the new sensor and it had metal fillings all over it just like the old one. This is when (insert sarcasim) it got fun. Had to split the tranny from the engine and blow it out with an air hose. Found the cause of the metal fillings (starter gear). Replaced the starter, and put it all back together and have had no issues in about 3500 miles. When you pull the sensor be kinda carefull with it and see if it has metal all over it. If it does try cleaning it off and putting it back in. If the problem goes away you got off easy. If not you may want to start looking for other things that are the cause.

~Curt

	Crank position sensor A crank sensor is a component used in an internal combustion engine to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control ignition system timing and other engine parameters. Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on the engine.