johnfkellogg

200XJ (73,000 and in great shape) was running fine; parked overnight -- NOW:

1. Fuel gauge sits at dead empty: Have fuel; cranks over; will not start.
A: Checked all fuses (passenger inside and under hood) All OK
B: Fuel Pump -- can not hear it However I took out fuel pump relay: Crossed 30 & 87 pins; turn on ignition key; pump sounds fine. REPLACED RELAY -- no sound of fuel pump and fuel gauge remains dead empty. I do not have a gauge to test the fuel PSI but doubt that would help anyway
C: Key check: insert key; press milage button; turn on key to run; speedo display runs through check 00000, 11111, 22222, through 99999 and then returns to current milage reading...NO error code given; and during run through fuel gauge and empty light are acuated and test out okay as do other instrument gauges.
D: Checked sending unit wiring connector at gas tank--visually ok and I cleaned contacts.
D1: I was unable to locate sending unit wiring within vehicle or under dash (wiring enters vehicle interior near gas tank.
E: All through above the fuel gauge remains at dead empty and vehicle will not start.

Appreciate the solution or ideas (possible electrical fuse??? or connection OR replace fuel sending unit as vehilcel is 12 years old and fuel sending unit looks to be original)

Thanks
John

kjc

I'd check for spark while cranking it. If it has spark, spray some starter fluid in the throttle body. If it starts, you have a fuel issue. If not, you might check your ASD relay(if applicable). And you said "However I took out fuel pump relay: Crossed 30 & 87 pins; turn on ignition key; pump sounds fine".. did you try to start it then? I don't know what pins 30 & 87 do (i'm guessing it runs the fuel pump) but if the relay switches those pins to 'on', then i'd check the power to that relay.

johnfkellogg

Thanks,

I have fuel injection and don't know how to check for spark. With the pumd on it still would not start. The 87 & 30 pins are within the fuel pump relay and if hotwired with the relay removed allows for the fuel pump to either function or not - mine functions.
The sending unit has both fuel pump and fuel gauge senso -- which I guess might be bad.

Have any thoughts as to where to buy fuel sending unit??? Jeep wants $538; Car Quest and Napa Auto Parts $337 ???????????????

Thanks for your response

John

tjwalker

The primary suspect is the crankshaft position sensor. When it fails in a certain way, you can lose the voltage gauge, the fuel gauge, or both. Sound familiar?

Here is a thread you should read:

http://www.jeepforum.com/forum/f11/c...ailing-639123/

Without the input signal from the cranks sensor to the computer, you will not have spark and you will not have fuel going to the fuel injectors (you may or may not have fuel pressure at the fuel rail)

You can test the crank sensor, but testing is not always conclusive. If you buy one, please do yourself a favor and buy it directly from Jeep! I cannot tell you all of the threads I have answered with people that have had trouble with some (not all) aftermarket crank sensors. It just is not worth the risk for the most critical engine management sensor on your Jeep. Buy an OEM sensor, it is money well spent for both reliability AND longevity!

I just ordered one from moparpartsonline and paid $60 for it. Cash and carry at a dealer and you may pay from $75 to $100.

johnfkellogg

Thanks,

I was unaware of the Crankcase Position Sensor (CKP) and reading the thread you sent, it does make sense this has failed as both the fuel gauge and (I think) voltage gauge do not work.

I was looking at the Camshaft Position Sensor (CMP) (located on the top of the oil pump assembly) today, having remembered the gentleman I purchased the vehicle from advising me he had replaced it. He stated this was not an uncommon problem with the 2000/2001 4.0L engines.

Come tomorrow, I will check out the CKP.

John

tjwalker

With the flaky gauges and the no start, the probability is very high that the crank sensor is in play here.

Try this. Unplug the crank sensor. There is a connector for it under the hood near the firewall / #6 injector. With the sensor unplugged, go back into the cab and turn the key to the ON position. Do your voltage and fuel gauges work now? If they do, that is smoking gun proof that the crank sensor is the culprit as this little test has been run with the crank sensor "out of circuit".

Let us know what you find!

johnfkellogg

Thanks to all who posted responses to my inquiry as based on your input a SOLUTION has been found. In simple terms:

The crankcase position sensor (CKP) failed (Jeep part #56027866 $116.75 for a 2000 Cherokee Sport 4.0 engine). Follow the advice given above: Once I unplugged the CKP the fuel gauge (& voltage guage) came back to life and appeared in working order. I replaced the CKP & the jeep started right up and continues to run just fine, with all gauges working properly.

Please note for the first couple or three start ups the Malfunction Indicator Lamp (MIL - yellow light in the shape of an engine) came on -- this is due to the Powertrain Control Module (PCM) having set a Diagnostic Trouble Code (DTC) that affects vehicle emissions -- visa vie the CKP -- indicating a problem was detected. Once repaired the PCM resets itself during the first three startups with the vehicle running at approximately the same level as when the failure occured.

The crusty, well seasoned parts manager said replacement of the CKP is by far the most common solution for a jeep which suddenly stops running.

I again tested the fuel pump and automatic rollover relays located in the PCM, as well as testing the fuel pump -- all were okay and were not replace.

Thanks to all for helping me work through this I am learning more about my Cherokke and appreciate experiencing the knowledge base of Cherokee Forum (as well as Jeep Forum which I was referred to for a pertinate posting on CKP).

John

tjwalker

Glad I could help.

Another happy cherokeeforum ending!

Oddballmotorsports

ok this is boggling my mind.. What does the fuel gauge have to do with the crank sensor??? I had to verify this. and its true can anyone answer why that happens, still working on getting mine running, but that is the first test I am going to do on it... tomorrow...

BlueRidgeMark

Every sensor affects the PCM, the computer that runs everything. If the PCM ain't happy, ain't nobody happy.

HOW unhappy and WHO is unhappy can be pretty interesting, and will vary depending on what sensor is bad, but the bottom line is, if sensors go bad, the PCM gets bad information, and if the PCM gets bad information, it does bad things.


By the way, if TJ says it, it's already verified.

Mcpiano

Stumped, just did complete overhaul and got ready to try
Turned ign key to on position, fuel gage came up, tested fuel rail for pressure, good, turned engine over, started immediately, ran perfect, sounded great noticed no oil pressure so figured it would take a minute to prime new oil pump, which I had primed before replacing timing cover, also noticed and light came on so killed it..... Now the weird stuff....
I waited few minutes turned key to on position, no fuel indication, spun over but no fire, removed all sensor connectors one at a time and only when I pulled the abs one did I get fuel gage and voltage meters back, spun over, fired once and, same no start condition, replaced and removed abs cable, now no fuel gage etc

dogkatcher

tell Midas that .. they scanned engine for an hour or more, could not find anything wrong, luckily didnt rape me $$wise on diag tests

but, they wouldnt listen when i mentioned this part .."oh no, that part just dies"

this is my 2nd cps gremlin .. 1st 1990 xj .. stalled random til it finally conked out for good, then codes thrown



current 1993 xj .. random stalls, no codes .. only 5-6 stalls though

too damn cold to do it myself in the snow .. risk dropping bolt into bellhousing with cold fingers / cold brain .. nearby shop charged me 1/2 hour labor

they even offered diags for $110 .. I said NO .. just replace it, waste of time testing

.. done deal .. love it .. seems alot of CPS issues lately


was yours the original ? look at old part .. #s on it

i got 252k miles on mine, believe its the original .. 0293 stamped under part #

BlueRidgeMark

You'll get better results on any forum if you start your own thread, rather than dragging up a old one.

If the old one has info that seems relevant, it's not a bad idea to link to it in your new thread.

Jeff Morris

grab some wires on the transmission and they was beer and it just died out on me and I've been dead ever since I did that test and I still have no gas gauge and security key light is on still and it will not start

lawsoncl

Hopefully he figured it out about 5 years ago. Do yourself a favor and go into your user control panel to edit options, and uncheck either the infinite scroll or show related threads. With both enabled, it's incredibly easy to end up in another (long dead) thread while scrolling down.