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Unread 08-22-2012, 09:43 AM   #1
rajacks
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1998 XJ Cherokee 
 
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Jeep Won't Start

I have similar but seemingly more serious problems. My 98' Jeep Cherokee XJ (4.0L inline 6) will not start as well. I don't know if the fuel pump is working while trying to start (don't know what that sounds like). I also don't understand the starting termionolgy used on this site such as the words "crank", "turn-over" and "spark". The best way I can discribe the way it starts is that it "Chugs" but will not take the last step and "fire-up". After I replaced the Camshaft Position sensor all my guages went dead. Bottom line......my jeep will not start. I have changed all the ignition related parts as shown below:

In order of replacement:
1. CPM
2. Distributor Cap
3. Rotor Button
4. Spark Plugs
5. Plug Wires
6. Ignition Coil
7. Camshaft Position Sensor
8. Crankshaft Position Senor (This was a BEAR to replace)

At this point I have no idea what else to do next. I am obviously new to mechanical work and this forum. Please HELP and educate me in simple terms I can understand.

And finally how do I check to see if I am getting spark plugs to fire?

Thanks in advance

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Unread 08-23-2012, 11:59 PM   #2
Reptile
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Check for spark: you take out the relay to the fuel pump which is located in the fuse box in the engine compartment (not required, but safer), unscrew one of the spark plugs, connect it back to its respective ignition wire. You want the spark plug to touch any metallic part of the engine in order to ground it, then have someone crank it up.

Check for fuel: hook up a fuel gauge at the service port of the fuel rail, should be in the vicinity of 40 psi, roughly. Or an alternative - less proper - way of checking it, throw some starter fluid in the throttle body (if starts = fuel issue).
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Unread 08-24-2012, 03:00 AM   #3
Hudson
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Quote:
Originally Posted by rajacks View Post
I also don't understand the starting termionolgy used on this site such as the words "crank", "turn-over" and "spark".
Crank - Literally that. You turn the key and all you hear is the engine "Cranking". It does not "turn over" it just cranks.

Turn Over - This is the step when your engine actually turns over and begins to run. Once you "crank" it, it should turn over. Your XJ does not "turn-over". If it doesn't turn over, you have a problem.

Spark - This just refers to whether or not you are getting a spark through your distributor cap, through the plug wires, into the spark plug. To test this, do as the other guy said. You can either pull one of the plug wires off the spark plug, and stick another spark plug in it and have someone crank the engine, you should be able to see it spark.

You can use a timing light to check spark if the light is flashing it is sparking.

Hope this clears up those terms a little bit.
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Unread 08-24-2012, 04:33 AM   #4
tjwalker
It's the crank sensor!
 
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I agree with Reptile that you need to adopt a "testing based strategy" to find root cause, rather than throwing parts at it which is inefficient and as you well know, gets expensive quickly.

Remove a plug, keep it attached to the plug wire, place the plug electrode near a good engine ground. Have a buddy crank the engine from the cab while you watch. You are looking for a strong, BLUE snapping spark. Yellow/orange/white indicates a weak spark, which may not be strong enough to start the engine.

If spark checks out okay (and ONLY if), then introduce a small amount of starting fluid or gas into the intake. If the engine starts and runs with this technique, you have identified a "fuel delivery" problem. You can put a fuel pressure gauge on the schrader valve on the fuel rail as well. For a 98, you must have 49 psi, plus or minus 5 psi for your engine to start.

I always start with the above two quick and dirty tests for a no start. It helps you ISOLATE your problem so you know what to focus on.

Good luck and keep us posted with your test results!
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Unread 08-24-2012, 06:59 AM   #5
rajacks
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Thanks for the replies.....I was starting to get concerned. I have checked and I do have spark. I have not checked fuel pressure yet since I assume I need some sort of guage. What type do you suggest and where can I purchase this device?
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Unread 08-24-2012, 07:04 AM   #6
tjwalker
It's the crank sensor!
 
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Quote:
Originally Posted by rajacks View Post
Thanks for the replies.....I was starting to get concerned. I have checked and I do have spark. I have not checked fuel pressure yet since I assume I need some sort of guage. What type do you suggest and where can I purchase this device?
Fuel pressure gauges, like all testing equipment, run the gamut for quality and price. You can probably get a cheap one for around $20 and you can likely also pay a few hundred for a real good one.

If I were you, I'd call around to parts stores in your area. Many of them, especially the big box stores, will rent you this tool very inexpensively. And the ones they rent out are generally a pretty decent quality tool.
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Unread 08-24-2012, 08:06 AM   #7
rajacks
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Thanks

I am also from Minnasota, St. Paul to be exact!!!
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Unread 08-24-2012, 10:45 AM   #8
pdcomm
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Hmmm , I've been wrenching for over 50 years and have never known cranking and turning over to be anything other than the same . Those meaning to crank , turn over or roll the motor without ignition .

Quote:
After I replaced the Camshaft Position sensor all my guages went dead. Bottom line......my jeep will not start.
I always check the last thing I did before the 'problem' started .
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Unread 08-27-2012, 06:33 AM   #9
rajacks
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Just so you all know......it ended up being a very simple problem........a bad ground wire! I changed all the above parts for it to be something that simple.
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Unread 08-29-2012, 12:29 PM   #10
rajacks
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Well the car is running but it is now throwing a MIL P0171 and P0138 code. What is the recommended first course of action? Change the O2 sensor or is there something else I should do first?
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Unread 08-29-2012, 01:29 PM   #11
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Quote:
Originally Posted by rajacks View Post
Well the car is running but it is now throwing a MIL P0171 and P0138 code. What is the recommended first course of action? Change the O2 sensor or is there something else I should do first?
The O2 sensor is suspect but I would suggest waiting before replacing to see if it resolves by itself within the next few running cycles. Since you restored your ground connections it is possible your computer is relearning the sensors' input calibration. Althought, make sure your wiring to O2 sensor isn't shorting out; this could yield more issues.
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Unread 08-30-2012, 09:58 AM   #12
rajacks
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I have been driving the car for the past four weeks and have not had a problem yet (knock on wood). Today the "Check Engine" light went off. I am not sure what to do with respect to this issue......looks like I will wait and see.
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Unread 09-04-2012, 10:49 AM   #13
rajacks
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To be conitued.....Part 2

Well the car is running fine but now I have a seperate (but maybe related) issue when the car is cold. Jeep starts and runs fine but when the car is cold the airbag light is lit on the dash and none of the gauges work. Once the car gets warm enough the airbag light goes off and the gauges instantly start to work. What does this mean??? Is there something I can do??? Help!!!
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