Jeep TJ 97 4.0L- No Start

ScottR

ScottR

It's never done.
Joined
Mar 21, 2005
Location
Raleigh, NC
I washed my jeep this weekend. I sprayed some water on the lower sides of the engine, in between the frame and inner fender. So things like the starter, distributor, coil did get wet. Then afterwards, it wouldn't start. It will turn over, but will not fire. I confirmed that there is no spark with an inline spark plug wire test light. I feel like there is fuel- fuel pump cycles and I can now smell fuel in the engine area- cylinders probably have plenty of gas since I have tried to start several times...
I replaced the camshaft position sensor (wafer thing in the bottom of the distributor) last night. And I swapped the ASD relay with the Horn relay in the fuse box. Still no change.
I tested the crank position sensor by turning the key to the 'On' position and then turning over the engine by hand- the fuel pump would cycle as I turned the engine. This was a test I saw on BleepinJeep youtube. Is that test sufficient or could the issue still be the CPS? I had a no start issue last January and that was resolved by replacing the CPS.

I have checked several other threads- answers vary; Crank Position Sensor (replace and just unplug for 5 minutes- tried the unplug thing), Map Sensor, Throttle Position Sensor, Ignition Coil...

What should I replace/test next?

I am trying to get this figured out fairly quickly. Our family is going to the CNC 4x4 Fall Bash next weekend and we are out of town this weekend...
 
Sounds like crank position sensor to me. Does the tach bounce while its turning over? I think I've heard that if the tach doesnt move its not seeing the cps.
 
I don't recall what the tach was doing while I was attempting to start- I will have to test that tonight.

I took the distributor cap off to replace the camshaft position sensor. I don't recall seeing moisture in the cap. Could be- will need to check.
 
ScottR said:
I don't recall what the tach was doing while I was attempting to start- I will have to test that tonight.

I took the distributor cap off to replace the camshaft position sensor. I don't recall seeing moisture in the cap. Could be- will need to check.
Click to expand...
Old muddin trick is to spray wd40 in the cap. Supposed to clear out the moisture. On mine IIRC the CPS triggers the ASD relay. If you turn it over by hand when the CPS passes the sensor it will trigger the ASD relay.
 
First, I would place the inline spark tester between the coil post on the cap and the coil plug wire. That will tell you if you have spark going onto the cap.
To test the CPS do the following
Unplug the coil 2 wire connector. Run a test light from the battery positive to the coil positive wire. Crank it over and if the test light flashes. If it does, the CPS is grounding and ungrounding the coil. If not, the CPS is bad.
 
ghost said:
Old muddin trick is to spray wd40 in the cap. Supposed to clear out the moisture. On mine IIRC the CPS triggers the ASD relay. If you turn it over by hand when the CPS passes the sensor it will trigger the ASD relay.
Click to expand...

Jody Treadway said:
First, I would place the inline spark tester between the coil post on the cap and the coil plug wire. That will tell you if you have spark going onto the cap.
To test the CPS do the following
Unplug the coil 2 wire connector. Run a test light from the battery positive to the coil positive wire. Crank it over and if the test light flashes. If it does, the CPS is grounding and ungrounding the coil. If not, the CPS is bad.
Click to expand...

Thanks for the additional tests. I should be able to run through all tonight and report back.
 
ScottR said:
Thanks for the additional tests. I should be able to run through all tonight and report back.
Click to expand...
Mine is OBD1 so not sure it works on yours but @Jody Treadway is the man with jeep knowledge. So I'd start with his on testing the CPS for that year.
 
I put a test light between the coil and the distributor cap- tried to start, no flashing light.
I put a test light between the #2 distributor wire and the positive lead of the battery- tried to start, no flashing light.
Tach never moved during any test.
I opened the distributor- bone dry inside.
I checked the three connections to the ECM- they are tight.

I did notice something different tonight- when I turn the key to the on position, the fuel pump runs continuously. Usually, when everything is working correctly, the fuel pump just runs for a second or so and then turns off. Also, gauges no longer work on the dash. Still get Engine light and Check Gauges light when I try to start. I know the battery is now getting a little low from all the test starts. Maybe that is causing some of these new issues. (battery still has enough power to turn over the engine at a decent pace) I put a charger on it.

I assume that with the first two failed tests above - I should replace the Crank Position Sensor.
I know most people say go with Mopar for sensors...where do you get it? I found an NTK at Rock Auto that can be here on Thursday. (I need one for a 1998 Cherokee 4.0L- I have the AW4 trans swapped into my TJ)
 
I would see if a parts store has an ntk, that way you can warranty if it fails. Rock autos return policy is shit and they’ll leave you stranded
 
Jody Treadway said:
What are the gauges doing, key on engine off?
Click to expand...
I have tried several times- it isn't consistent....

Sometimes with the key on- the gauges work and the fuel pump cycles just for a second (this is what it should do).
Sometimes with the key on- the gauges do not work and fuel pump runs continuously. (This happens a majority of the time.)
 
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ScottR said:
I have tried several times- it isn't consistent....

Sometimes with the key on- the gauges work and the fuel pump cycles just for a second (this is what it should do).
Sometimes with the key on- the gauges do not work and fuel pump runs continuously. (This happens a majority of the time.)
Click to expand...
Try unplugging the sensors with a 5 volt reference signal, one at a time and observe the gauges
TPS, cam sensor, MAP, IAT, ECT and the clock spring.
 
I was able to remove all sensors one by one- no change, don't have gauges with any one of them removed.
I was able to unplug the clock spring. Gauges still do not work.
 
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ScottR said:
I was able to remove all sensors one by one- no change, don't have gauges with any one of them removed.
I was not able to unplug the clock spring. I need to remove the steering wheel for that- will need to get a puller.
Click to expand...
Should able to access the connector by removing the steering column shrouds
Also look for the O2 sensor wiring to be melted on the pipe. Especially the rear
 
Jody Treadway said:
Should able to access the connector by removing the steering column shrouds
Also look for the O2 sensor wiring to be melted on the pipe. Especially the rear
Click to expand...
You are right- I was able to remove the shroud to unplug the clock spring- no change. Gauges still don't work.
I checked the wiring for both O2 sensors- looks fine.
 
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I was finally able to mess with the jeep today. A buddy, Ronnie, in Wilmington suggested to swap out the ECU to see if that is the issue. He had a few used ones to offer for the cause. I met him in Warsaw to pick them up. With the help of Ron and @BRUISER we double checked some items and swapped in the first ECU- one for a TJ with a Manual Trans - a perfect swap for my jeep since my jeep initially had a manual. Still couldn't get the jeep to start. Then we checked the battery sensor- we were double checking everything. Then, we put in the XJ with Auto ECU- the jeep fired up and ran!!! So, the issue was the ECU. (I can only assume that the first ECU we swapped in was bad.) I am getting a Check Engine Light- throwing a code for the Transmission Control Module. So, I will need to get an ECU for a Manual. But, the big thing is - we identified the issue. I appreciate everyone's help. @Jody Treadway - thanks for all your input. I definitely learned a lot on how the 5v signal goes through the various sensors. I have an extra CPS to throw in my electrical tool kit in the Jeep. Only a matter of time before that gives out again.
 
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