2000 4.0 TJ cranks but won't start

brodyrife

brodyrife

New Member
Joined
Jul 19, 2020
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16
Location
Pennsylvania
My jeep was running fine a week ago and I went to start it the other day and it just cranks and doesn't start. I recently replaced the fuel pump about 2-3 months ago and when you turn the ignition to on you can hear it prime. I hooked up my scan tool and got codes p0152, p0155, p0161, p0131 and those are all oxygen sensor codes. I cleared those codes and still have a crank but no start. The jeep also has newer spark plugs. Any help is greatly appreciated.
 
brodyrife said:
My jeep was running fine a week ago and I went to start it the other day and it just cranks and doesn't start. I recently replaced the fuel pump about 2-3 months ago and when you turn the ignition to on you can hear it prime. I hooked up my scan tool and got codes p0152, p0155, p0161, p0131 and those are all oxygen sensor codes. I cleared those codes and still have a crank but no start. The jeep also has newer spark plugs. Any help is greatly appreciated.
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Do you know what brand fuel pump was installed.
 
brodyrife said:
Just an oem style one from NAPA
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I don't have any direct experience on this front, but you'll find that everybody here is going to take a dump on any non-Bosch fuel pump. Regardless, have you checked for fuel pressure?
 
hear said:
I don't have any direct experience on this front, but you'll find that everybody here is going to take a dump on any non-Bosch fuel pump. Regardless, have you checked for fuel pressure?
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I don't have a gauge and being in college its a little more difficult to get to an auto zone to rent one. I however ordered some starter fluid and I'm gonna see if this gets it to turn over at all to verify if its a fuel problem or not.
 
brodyrife said:
I don't have a gauge and being in college its a little more difficult to get to an auto zone to rent one. I however ordered some starter fluid and I'm gonna see if this gets it to turn over at all to verify if its a fuel problem or not.
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Good start,

O2 sensors do not typically create a no start issue so when you mentioned fuel pump replacement we tend to see a lot of the off brands create problems. Delphi and Bosch are preferred.
 
Fuel, air and spark. Keep it simple. Starting fluid is always a good starting point. After that then check for spark.

Poor man's test is to pull a plug and ground it to the head and have someone crank.
 
Since ALL the codes are O2 sensor related; I would check the wiring harness going to the O2 sensors.
Inspect the wiring harness supplying communications from the ECU to the sensors.
This harness passes between the valve cover and the firewall routed around a threaded head stud on the drivers rear corned of the head. The threaded head stud is known to rub thru the split wire loom and wiring insulation causing intermittent shorts to ground.
 
Boinked said:
Fuel, air and spark. Keep it simple. Starting fluid is always a good starting point. After that then check for spark.

Poor man's test is to pull a plug and ground it to the head and have someone crank.
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What do you mean ground it to the head?
I have a coil pack you unbolt from the head covering the spark plugs no wires going to it so would I be able to do this?
 
Sorry to hear about your jeep issues, but you're on the right path as far as ruling out the spark issues. You still having Communications with your ECM is a plus and you could very well have bad ECM Drivers (inside the Computer), which activates your Fuel Pump Relay and ASD (Auto Shutdown Relay). Very common on these older jeeps,

If you need anything else, don't hesitate to contact us!! More than happy to assist.

Hope this helps! ACS
 
Check your fuse box in the engine bay. Make sure any fuse related to fuel isn’t burned out.

I had this issue on Saturday. My fuel pump line got caught in the suspension springs or some random moving components and it tore through the wire causing a short.
 
The starter fluid didn't do anything so I pulled the coil rail and put a spark plug in it and I didn't see any spark. Should I replace the whole rail? Is it common for the whole coil rail to fail like this?
 
There are 3 coils in the rail. Unlikely they are all bad. 1 coil fires 1 and 6, another 2 and 5, and the other one 3 and 4.

The crank sensor is used by the PCM to fire the coils. That would be the first thing I would check.
 
I looked up grounding point for the some of the more sensitive electronic items.. ignition, O2 sensors and computer. they are tied to the g105 terminal, kinda surprising to me how so many things end their circuit there. a critical grounding point for sure.

have a look at this thread and review post #41 & 43. 43 shows a few wiring diagrams of just a few components of the many others involved in that specific ground point shown in post #41. https://wranglertjforum.com/threads/g105-ground-location.32058/page-3

id attempt taking the nut off and hitting the stud and ring terminals with a wire brush and scrub them clean.
 
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brodyrife said:
The coil rail didn’t fix it. I’m gonna try crankshaft position sensor. Can anyone recommend one?
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I posted a link above for testing both the CKPS and CPS; don't just replace the part without knowing it is the problem.
IF after you perform the testing and you determine one of them is bad; then I would suggest the OEM Mopar replacements instead of the Chinese (AutoParts store) knock offs.

https://www.amazon.com/dp/B006EFUF2I/?tag=wranglerorg-20
 
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I got my jeep to start, I replaced the crank shaft position sensor (I got one from my local Jeep dealer) and it finally started, but my Jeep is running really rough and keeps throwing the code for the crank shaft position sensor. It also stalls out and is basically un-drivable. Does anyone know what I should do next? Thanks.
 
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