'00 XJ Engine cuts out and dies

OK - here goes again...

A few weeks ago, I go to start my Jeep and it cranks and cranks but won't start. No CEL, no error codes, yet it won't start. I moved it, facing downhill, and the next day it starts but only runs for a few minutes and dies. Restart and it runs for 10-20 seconds and dies. It will die when your driving down the road at 40mph or just sitting at idle.

I replaced the ASD relay (starts, runs, dies).
I replaced the fuel strainer (starts, runs, dies, runs, dies, runs, dies....)

My Jeep has the PITA(!) all-in-one fuel pump module on top of the tank. Thanks to the post on JEEPFORUM on dropping the gas tank! After replacing the strainer, I even hooked up a hose from the pump outlet to the return line and ran the pump (in the tank) for two minutes before re-installing everything.

So, for some reason, the Jeep is still deciding to shut things down. HELP!

I've also checked the following:

Coolant sensor - unplug and aux fan kicks on, engine still runs, get CEL and error code for open circuit.
Intake Air Temp - unplug and no effect, engine still runs, get CEL and error code for open circuit
Idle Air Controller - unplug and no effect, engine still runs, no error code.
TPS - unplug and engine surges once, get CEL and error codes for high and low open circuit.
MAP - unplug and engine surges up and down, get CEL and error code for open circuit.

Before I go and spend $250 on a new pump module, is there anything else that could be causing this problem? (starts, runs, dies, gets progressively worse, give it a few hours or a day and it does it all over again) If it was insufficient fuel, would it just totally cut out like that. And then when I go to restart, there is no voltage to the injectors. If its not fuel starvation, then something is "tripping" and then eventually resets.

Some specific questions:
Fuel pressure - is there a fuel pressure sensor? They don't show one in the Chiltons manual and I couldn't find one.
CPS - how do you get to it and can it be removed without dropping the engine?
Ballast resistor - where is it on the 2000 model year?
Fuel pump - anything else that be causing this problem?

Thanks in advance for any help/suggestions.

hmmm ....



checked your battery?

There is no fuel pressure switch.
Get a gauge and check the fuel pressure, don't just guess.

Bowzer - no, the battery is fine - I could probably crank the engine for five minutes straight. But, just to be sure, I topped off all the cells and cleaned the terminals. No change.

Langer1 - I don't have a "fuel pressure gauge" or anything else that fits the fuel rail port - I'll have to borrow or rent one since I can't drive the Jeep anywhere.


After reading through a lot of other forums, I just realized something else was amiss. The fuel tank is not pressurizing. It used to be that the fuel cap was a bit snug and gave a whoosh when you took it off. Now it seems to come off easier and no whoosh. It was doing this before I dropped the tank to replace the fuel strainer.

Before anyone asks, I made sure some joker didn't pull out the o-ring on the cap, and the check valve in the cap seems to be working properly.

So... can anyone explain how the Jeep pressurizes the tank? Would a loose or missing gas cap stop you dead in your tracks, unable to restart? At idle, the EVAP solenoid is clicking at a steady rate, about two or three clicks per second. The Leak Detection Pump clicks a few times at start up.

Thanks again...

You are going to have to do a little diagnostic work before anyone can help you. Fuel pressure would be a good start. Unfortunately the y2k XJ has DIS so there is no easy way to check for spark. The evap system could totally fail and the truck shoould still run fine; albiet with the mil lamp on.

mattmankow - I'm trying to rig something up so I can check the fuel pressure, but it doesn't seem to be acting like that's the problem. It doesn't slowly cough and sputter, it just dies, and I'm not getting any error codes for lean mixture or the O2 sensors. But I'm going to check...

I'm getting spark because I can spray some starting fluid in and it fires and tries to run. I can crank and crank with no response, spray some fluid it, and then it tries to run, so I don't think its a bad crank or cam sensor. Its getting spark.

After it dies, I crank and crank but it won't restart. I checked the injectors and found that there was no juice to any of the injectors. I replaced the ASD relay and still no luck. I can turn on the relay by jumping the pin from the ECU harness and get juice to all the injectors, so I know all the wiring is good. Let it sit for a day and all is forgiven.

So... what could cause the ECU to go into Auto Shut-Down mode and not throw an error code? Anybody know?

And... how does the fuel tank pressurization work? Could that be causing all this?

Thanks again...

A WOT signal turns the injectors off.
If the engine floods holding the throttle wide open, when cranking turn's the injectors off.
BTW injectors need pressure to operate, if the pump stops they quit instantly.

langer1 - how do I measure WOT signal? I've got a multi-meter but no manual. When it finally did decide to run, I disconnected the throttle position sensor and it kept running (and gave error codes).

I don't even touch the throttle while starting because its fuel injection. Like I said, I can crank and crank with no start, spray a little starting fluid in and get it to kick a little, then goes back to just cranking over. And no fuel smell at the tailpipe. So WOT leading to flooding leading to injectors off... just doesn't add up. But I'll check WOT signal if you say so...

Last night, after towing it home, it decided to start up again. I didn't even get in the car, just reached in, put the key in the ignition, and started it up. It idled like a kitten for about five minutes, while my neighbor and I tried to figure it out. Then, it just stopped, and wouldn't restart.

And I can understand the injectors not (mechanically) working without sufficient fuel pressure, but my questions is why the ECU is shutting down the ASD relay and not even sending power to the injectors in the first place. If there is no fuel pressure sensor, why are the injectors not (electrically) working?

Fuel pressure regulator? Check valve? I'm just trying to nail this thing down before I start throwing more money into it.

The WOT is programed that way so you can get a flooded engine started.
If the injectors keept delivering fuel you could never start a flooded engine.

OK - so how do I tell if that is what's happening?

Right now, the Jeep is deciding that it will start up and I have an OBD-II code scanner (Actron CP9145 Super AutoScanner) which also shows real-time data. What can I be looking for?

When it does quit, there is no check-engine light and no error codes. When I go to restart, it cranks and cranks but won't restart. The fuel pump comes on but no power to the injectors, and no error codes. I've tried the trick of turning the key on and off several times to build fuel pressure, but no luck.

Craig said:

OK - so how do I tell if that is what's happening?

Right now, the Jeep is deciding that it will start up and I have an OBD-II code scanner (Actron CP9145 Super AutoScanner) which also shows real-time data. What can I be looking for?

When it does quit, there is no check-engine light and no error codes. When I go to restart, it cranks and cranks but won't restart. The fuel pump comes on but no power to the injectors, and no error codes. I've tried the trick of turning the key on and off several times to build fuel pressure, but no luck.

Click to expand...

Running out of fuel may happen so quickly no code is set.
Watch the o2 sensor for a change just before it quits.
Wait you did say you loose power to the injectors. :wierd:
Ok the ASD relay will also shut down if the signal from the cps is weak or missing

This thread has me very interested right now as I'm having a similar situation with my 2000 XJ. It's happened three times now -- just up and dies without any warning (at idle in Park or Drive). It will, however, start right back up and stay running. Specs: 2000 XJ, AW-4 auto, 60K on the odometer, all stock.

OK - I went to Advance Auto and dropped $40 on the fuel pressure gauge. The beast decided to start and I got 48 psi at idle. In fact, it kept a fairly steady 48 psi as I revved the engine.

I hooked up the scanner and waited and waited.... and the d*** thing ran 90 minutes without a hiccup, till I shut it off.

cold idle at 720 rpm and oil pressure at 32 psi
warm idle at 660 rpm and oil pressure at 22 psi
hold at 2,000 rpm and oil pressure at 48 psi

MAP ran 9~12" Hg
coolant steady at 212 deg
IAT ran 150-160 deg
Ignition advance - 10 deg at idle, 34 deg at 2,000 rpm
LT/ST FTRM codes (fuel air ratio correction factor) ran +/- 3%
Fuel system ran in closed mode
O-2 sensors danced around from 0.1 to 0.7 volts

Could this be something as simple as water in the gas? Will the in-tank filters let water pass through? Could too much water choke off the fuel filter and cause the engine to quit?

Capt. Nemo said:

This thread has me very interested right now as I'm having a similar situation with my 2000 XJ. It's happened three times now -- just up and dies without any warning (at idle in Park or Drive). It will, however, start right back up and stay running. Specs: 2000 XJ, AW-4 auto, 60K on the odometer, all stock.

Click to expand...

90% of the time it's the CPS.

langer1 said:

90% of the time it's the CPS.

Click to expand...

I was reading somewhere else where it could be the battery also. We've had the Jeep for over three years, plus the two before we owned it, and it looks like it still has the stock battery. Could a battery that is going out "hiccup" and not provide the proper voltage to the computer and cause the car to suddenly die? The car doesn't die at speed, which would tell me the alternator is compensating at higher RPM's. Yes, no?

Sorry to hijack, just brainstorming.

Oh, and as asked before, where is the CPS and how do you check it? I have a feeling that testing it is going to be futile, since the problem is very intermittent (days can go by before it will happen).

Capt. Nemo said:

I was reading somewhere else where it could be the battery also. We've had the Jeep for over three years, plus the two before we owned it, and it looks like it still has the stock battery. Could a battery that is going out "hiccup" and not provide the proper voltage to the computer and cause the car to suddenly die? The car doesn't die at speed, which would tell me the alternator is compensating at higher RPM's. Yes, no?

Sorry to hijack, just brainstorming.

Click to expand...

Does the Radio and lights also go off? If not then I doubt it's the battery.

Well, in my case, its just the engine that dies. Everything else still works. Its cut out while (1) sitting in the driveway idling, (2) driving down a dirt road at 10 mph, and (3) drive down the highway at 50 mph. Something seems to be tripping the ECU and causing it to kill the engine.

Its not the CPS. I've gotten pretty good at spraying just enough starting fluid in to keep it running.

But as to the battery question - yes, if your battery was giving out, you might be able to run off the alternator at normal driving speed, and then have the car die when you come to a stop. I had this happen once - put too many fog lamps on, drained the battery, and as soon as a came to the first stop sign, everything went black.

Capt. Nemo said:

This thread has me very interested right now as I'm having a similar situation with my 2000 XJ. It's happened three times now -- just up and dies without any warning (at idle in Park or Drive). It will, however, start right back up and stay running. Specs: 2000 XJ, AW-4 auto, 60K on the odometer, all stock.

Click to expand...

I get it also on my 00XJ, but I am always able to restart it immediately. (for now, muuahahah)

No lights, nuttin. Like the key is off. Restart it and all is well.

Try replacing the battery just for kicks. When I've had strange things happen in the past somehow it comes back to the battery......

My wife tells me that the radio continued to work after the car died. The car will start immediately after it dies and will work as if nothing happened. The radio has a very low amperage draw, so even if the battery was going, it could still provide enough amperage to run the radio. Nothing else in the car was on.






wierd.