01XJGirl

Jeep has been sitting since 2019 started and moved a few times since. Was running and drove less than a month ago. Put in brand new fuel pump.
I have a 99 grand Cherokee that runs. Been swapping parts to the 01 XJ from the 99 grand. Parts are: (all were tested to see if they worked before putting them on)
fuel rail/ injectors
power steering pump
camshaft synchronizer and the sensor
coil pack
Crank no start issue started about a month ago. No spark or fuel. I’ve read and watched everything I can about this issue. Checked everything I’ve come across. (Sensors, fuses, relays, individual pcm wires to their appropriate harnesses, cleaned/dialectic greased connections) No codes either! The only thing that worked was resetting the pcm. It started 2x yesterday after resetting the pcm. Today, crank no start again. I’m thinking I need a new pcm. Before spending the 300, any advice! Thank you!

awg

Things may be different on the later models, but my spare '96 decided it wont start

So far I have ascertained the fuel pump does not whir for 3 secs when key goes to Start or Crank, but the fuel pump relay clicks out after 3secs

I believe the ASD relay will cause the PCM a time out signal if it does not receive the correct inputs

That is as far as I got, except I am of the understanding the main culprit for this will be a failed Crank Position Sensor

You may wish to perform some further tests and diagnostics, including on the CPS,
I am of the understanding it can fail without codes, and the fail mode is no spark or fuel (others may chime in on this point)

In my case, I will perform some further test and diagnostics before replacing any parts, but I do have a spare Crank sensor, fuel pump and PCM

Fortunately this is not my daily driver, it is my spare parts savior, it all takes time

cruiser54

How's the battery?
How about doing something like this?CRUISER'S MOSTLY RENIX TIPS

CONNECTOR AND RELAY/RECEPTACLE REFRESHING

OCTOBER 30, 2015 SALAD 38 COMMENTS EDIT



I suggest unplugging EVERY electrical connection in the engine bay you can find, whether engine related or not, and spraying it out with a , visually inspecting the terminals making sure they haven’t retracted into the plastic holder, and then plugging it back together.

There’s a critical 10-pin connector for the front lighting system located in front of the air cleaner and behind the left headlight assembly. Don’t miss that one. Also be sure that the connectors to the ballast resistor mounted near the air cleaner housing are clean and tight.

ALL of the relays should be removed, the terminals wire-brushed until shiny, and the receptacles sprayed out with contact cleaner. Then plug them back in. I do this on every Renix Jeep I purchase or work on for someone else.

awg

I agree with Cruiser about the connectors and grounds, I have done some connectors, and refreshing and checking all ground wires is next on my schedule

Then I will check if I have spark.

If I have no spark, and no fuel pump, I will probe the CPS and check against FSM data

If I have spark, I will go down the direction of the fuel pump and other things

crank with no spark and no fuel, my understanding a poor ground, bad wiring or connector, failed PCM, or failed CPS would be most suspect to cause this fault

be aware that a short circuit in a sensor or its wiring will pull down the 5v supply to all sensors on that circuit, causing a PCM sensing problem

Test for 5v on the CPS power wire

My understanding is if other sensors fail, you will often get a OBD code, but a short will mean the PCM may not function properly, and can fry an output circuit within it

Roler

Awkward scrambled posts in this thread
Plus it's a bit unlike the usual awg

awg

maybe I posted late at night or something

in any case, my explanation is aimed at resolving a "crank, no start situation"

I have that in my spare '96 XJ and used the tests I have done, (and will do)

* test for operation of fuel pump and spark at plugs

* test relay operation

* test sensors and wires

Using the FSM

I hope that is clear to the OP, who has not responded with any clarifying facts as yet

awg

crank, no start 101

* grounds good

* have spark

* remove fuel pump relay, have 12V at fuel pump relay + socket , as expected and 12V when ignition is on for 3 secs, and when cranked

*swap ASD and FP relay, no joy

* as per FSM, insert 12V backprobe wire into cavity 87, and re-insert relay, 12v output to FP is present when it should be

* disconnect FP connector under car, insert probes into black and orange wires, (have assistant who arrived crank key ) ...12V is present

* stimulate spare fuel pump with 12V on above wires...it whirs

* stimulate fuel pump connectors with 12V...it does not whir!

My preliminary verdict....failed Fuel pump

previously replaced the pump body with a '95 pump (I think), this vehicle was very cheap to buy, as it had the fuel tank and brake MC in the back, about $50 each and I had it going

I will replace the fuel pump assembly with the spare that I have, and expect it will now start...the spare pump may even read the fuel level

I will fit a new pump body to the '96 assembly, and see if i can work out why the fuel level sender circuit is kaput

This is my "spare" XJ, it is normally fully operational, and I keep it that way, so I can use it for spares or a test bed for my DD

Roler

Mate, you still got me a bit stumped and not seem the usual awg LOL
Besides the 101 (which is good btw), why are we now talking about YOUR spare 96's issue and not the OP's!? LOL

I could be completely wrong, but the awg I know would never kind of hijack a thread to talk about his own issue but would be to the point, with clear advice and throw in some electric knowledge (being from tech background if IIRC)

But maybe I'm just getting older (and not wiser) and not reading this right LOL

awg

I am fearful the italic bit might be right

Just to clarify

The OP has a crank, no start. I also have a crank, no start

I have clearly outlined the testing procedure for this problem, and the OP can follow this, or not, to suit themselves

It matters not at all whether it a '96 or '99, spark and fuel need to be verified, the procedure up to this point is identical

As the OP seems to have gone awol, its not really a hijack, more legitimate salvaging an abandoned vessel

Hopefully my XJ will soon be a goer when I fit the fuel pump, and I will keep youse all updated

If the OP requests further assistance, I will endeavor to guide them from afar

Roler

Haha
now thát's the ol' awg

awg

I read the OPs post again, out of respect, and I can see they know and have done lot
That would be very time consuming and frustrating

I can only suggest, wiring, crank sensor, or PCM

It would be slightly possible to do further testing, but in my opinion, one would access to an oscilloscope (and knowledge to use it)

You can test if the crank signal is being disrupted

Original quality crank sensors are expensive

I am going to assume you have swapped it with a known good one, a new one, or tested it to your satisfaction

That leaves wiring or PCM

Let us know

************************************************** ***************

Update;

My spare '96 will not start as the fuel pump is failed

When I withdrew it, the whole assembly looks like it has bathed in the ocean for a long time

This is disturbing and I will have to withdraw the tank and inspect it. I cleaned the tank and put a new pump body on, its maybe 8yrs ago

It has sat in my yard that time, always a goer until now. It should have only a few gallons of fuel in it (level sense dont work). I am hoping I will not find it with water inside

Once the tank is out and cleaned, I may fit my spare FP assembly. I am going to try and de-rust and rehabilitate the unit that was in there

As I have a '96 the regulator and assembly are one in-tank unit

You must have a spare, as if it fails, you will be cactus

ordered a Bosch 93-96 pump body and kit for $A65

I will start new thread if and when I rebuild and get working all aspects of the '96 assembly, including fuel level and sense circuit