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No start... cranks though

Tenny

NAXJA Forum User
Location
Houston, TX
So a few weeks ago I replaced my exhaust manifold and my head gasket trouble shooting for a cooling issue...

After putting it back together, I was running it for about a week (didn't solve the over-heating issue... but that's another story all together). At one point I drove it for about 30-40 miles without any issues. Eventually I went to Costco which is about 2-3 miles, and it just died on the way home. I figured it ran out of gas as it was really low. Since then I've put two gallons in and it still won't start. So that isn't the issue.

I read online a bit, and read a bout the CPS Sensor being a common issue. I checked for a spark and there was no spark. I have both fuel and voltage gauge. I've unplugged and plugged in the CPS, and it didn't have any effect on it. I have also disconnected the battery to reset the ECU, and no luck.

I've looked around for loose hoses / connections but haven't been able to find any...

I'm pretty poor, and lacking motivation (esp after all that I did just the other week for it...) so looking for any assistance in where I should look. The more I can "test" without buying parts is obviously preferred. Also I'm doing all this work by myself and don't have any assistance... so sometimes doing two things at once can be a huge problem. :(
 
Please always include the BASICS--year/engine/etc.
 
Err, forgot I deleted all that from my sig (and didn't attach it apparently!)

1994, 4.0 HO, AW4. Engine is 100% stock.
 
Check for 12 volts to the primary side of the coil. That comes from the ASD relay, which gets it from the ignition switch. The PCM provides the ground to energize the ASD and Fuel relays.

That is what I would check first.
 
Ok, so I'm not the most technical person out there, def don't know too much about the electrical systems of these vehicles, but I went out there and played around based on what you said.

I unplugged the coil, and on the connector side one of the terminals gave nothing out, and the other gave just a hair under 12 volts. I assume that's the "primary side" and the terminal that gave out nothing was just the negative. I wasn't able to fit my multimeter into both at the same time so I can't verify that 100%.

Then on the other side of the coil, it was only outputting about 6 volts. Is that normal? I would imagine that it should be 12 volts?

BTW: How do you like Grants Pass? My brother lives in Crescent City and is moving to either Medford or Grants Pass in the next few months. He has a 5.9ZJ & a 99 (I think).
 
Ok... so maybe I was completely wrong with the CPK Sensor...

I was working on the one near the distributor not the one on the bell housing.

I just tested the ohms on the one on the bell housing, and I was getting 3.43 M... which would be low resistance which means it's bad... right?

Also forgot to note that the voltage I was getting after the coil... that was with the key turned, but not trying to crank (as I'm doing this by myself... need more hands if I was to do that... and from what I read it'd have probably destroyed the multimeter).
 
The resistance of the CKP should only be about 300ohms (+/- 50) I think? So resistance is way HIGH!
 
Yeah, the 12 volts to the primary side is correct, that tells us the ASD relay is functioning, as well as the ignition switch. When the primary side of the coil collapses its field the secondary side shoots out the spark. You can measure the resistance of both the primary and secondary sides of the coil to see if it is within specs.

You may have a Diamond or Toyodenso coil.

Diamond coil: primary resistance 0.97 to 1.18 ohms; secondary resistance 11,300 to 15300 ohms.

Toyodenso coil: primary resistance 0.95 to 1.20 ohms; secondary resistance 11,300 to 13,300 ohms.
 
The resistance of the CKP should only be about 300ohms (+/- 50) I think? So resistance is way HIGH!

No, Renix 87-90 is 200 ohms + - 75 ohms or 125 to 275 ohms.

The 1994 should have infinite resistance. Measure between B and C of the connector, meter on 1k to 10k ohms--it should read as an open circuit.

Terminology is a problem with this stuff. CPS/CKP are both used for the crank sensor, aka engine speed sensor.

CMP or CPS are both used for the synch sensor in the distributor.
 
No, Renix 87-90 is 200 ohms + - 75 ohms or 125 to 275 ohms.

The 1994 should have infinite resistance. Measure between B and C of the connector, meter on 1k to 10k ohms--it should read as an open circuit.

Terminology is a problem with this stuff. CPS/CKP are both used for the crank sensor, aka engine speed sensor.

CMP or CPS are both used for the synch sensor in the distributor.

Yeah I was confused by the terminology reading too much and not understanding enough.

So the multimeter I have is a Fluke 73, not sure which series (not home right now). I'm finally reading the manual online, as I had the range on "Automatic" mode. So when I get home, I'll try selecting the 1k-10k ohm range and test that again.


Yeah, the 12 volts to the primary side is correct, that tells us the ASD relay is functioning, as well as the ignition switch. When the primary side of the coil collapses its field the secondary side shoots out the spark. You can measure the resistance of both the primary and secondary sides of the coil to see if it is within specs.

You may have a Diamond or Toyodenso coil.

Diamond coil: primary resistance 0.97 to 1.18 ohms; secondary resistance 11,300 to 15300 ohms.

Toyodenso coil: primary resistance 0.95 to 1.20 ohms; secondary resistance 11,300 to 13,300 ohms.
Will try, following this basic guide: http://autorepair.about.com/od/troubleshooting/ss/coil-test-ohm.htm

Should I have an specific range set on it?
 
Yeah I was confused by the terminology reading too much and not understanding enough.

So the multimeter I have is a Fluke 73, not sure which series (not home right now). I'm finally reading the manual online, as I had the range on "Automatic" mode. So when I get home, I'll try selecting the 1k-10k ohm range and test that again.



Will try, following this basic guide: http://autorepair.about.com/od/troubleshooting/ss/coil-test-ohm.htm

Should I have an specific range set on it?

For both the primary and secondary sides choose a range that will be close to but slightly over the highest value you are testing for.
 
Ok, so the multimeter is throwing a little curve ball at me as it doesn't have specific "ranges"

Here are the ohm choices:
0L. Ohm
0L Ohm
0.L K Ohm
0L. K Ohm
.0L M Ohm
0.L M Ohm

I'm guessing the K / M mean Kilo/Meg.

Anyways with the CPS, when I have it on either of the ones with K, I get no reading just continues to say 0.

As far as the Ignition Coil, I can't tell which model it is. The only thing it says on it is "5234610" and a "2123" in small letters on that.
Primary: 1.1
Secondary: 11.99 k ohm (11,990 I guess?)
 
Ok, your number look good for either brand coil.

And zero or infinite says the crank sensor is good.

Starting to think harness/PCM is your problem.
 
Tenny what the hell are we going to do with that Jeep I think we need a work party for your bucket of bolts. First overheating now it wont start this is giving the cherokee a bad name. Let me know if I can help I doubt I could figure it out but I can spin a wrench and replace parts. :D
 
Ok, a few new updates...

My dad came out yesterday with his Jeep so I had the first opportunity to actually work with the assistance of someone else, we made sure there was no spark and there wasn't. Then we plugged a spark plug wire directly to the coil, and tried firing and nothing.

We repeated the procedure on his Jeep with the plug / wire off mine and it worked.

I double checked that I was getting 12 volts into the ignition, and I was, the other wire (probably the control or whatever) was getting zero, but while my dad turned the engine over it did jump around a bit, but I couldn't get an accurate reading.

So I called a friend on here for a little assistance, he confirmed what we were thinking that it could be the coil. After much time I convinced my dad to let me swap coils out of his jeep into mine, as they appeared almost identical ('97 TJ 4.0L). Swapped the coils and it wouldn't fire. Replaced his back into his and it worked fine still.

At a loss now, looking for more ideas.
 
Ok, everything you have done so far would indicate that the ignition switch, the ASD relay, the crank sensor,and the coil are doing their jobs or are within specs.

That is leaving us with the PCM or ignition spark distribution.

Lets look at distribution. First, for grinz and giggles, pull the coil wire from the center of the distributor and use that to check for spark with a plug grounded to the engine. Got spark? If yes, then pop the distributor cap and check the center contact, as well as the rotor--look Ok? If so, crank the engine over with the cap off--rotor turning?

Post up.
 
s with the PCM or ignition spark distribution.

Lets look at distribution. First, for grinz and giggles, pull the coil wire from the center of the distributor and use that to check for spark with a plug grounded to the engine. Got spark? If yes, then pop the distributor cap and check the center contact, as well as the rotor--look Ok? If so, crank the engine over with the cap off--rotor turning?

Err meant that's what we did. We put the spark plug directly on the ignition coil and grounded it looking for spark. No spark.
 
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