EdZ

2000 XJ Sport 4.0L... Replaced the fuel pump motor now it has 46 psi and holds at 40 for over a minute at the fuel rail... No error codes or check engine light although the battery had been disconnected to clean the posts... It ran for about 1 minute right after I finished the fuel pump replacement then it died while idling... Now there is no sign of life while cranking... Checking for spark would require me to remove the coil pack bar and is rather difficult to get the connector disconnected (no room between the firewall and the coil bar)... I ran out of day light before I could ohm out the Crank position sensor... If that unit checks out OK what would be the next are to check ??? Cam position sensor maybe ???
Thanks much,
Ed

tjwalker

Try introducing a small amount of gasoline into the intake to see if it fires. If the engine starts and runs for a few seconds, that would at least verify you have good spark.

The history of this repair is very important here. How did you troubleshoot the problem was fuel related and what were the exact symptoms?

I'm playing devil's advocate here and it is possible that the original problem was not fuel related, but rather ignition/spark related.

Good luck and keep us updated!

EdZ

I had sprayed some WD40 into the throttle body originally... That's whatlead me to check for adequate furl pressure and leading to fuel pumpreplacement... Upon getting new pump in the engine ran great for about 1 minuteand then just died while idling... The part that bothers me most is the lack ofany codes... It tells me the ECU is thinking all is within parameters... Ifanything is not present (like crank position sensor) shouldn't I have an errorcode (like 320)... Also isn't there a code for having recently disconnected thebattery that I should have as well ??? I’ll put some gas in the throttle bodyand see what happens…

RTorrez1

Make sure that you have a good strong blue spark. BTW You fuel rail should hold the pressure for a lot longer then a minute. What brand of fuel pump did you put in. Hope not an Airtex. They are garbage and can be crap new or fail prematurely.

EdZ

It was just the electric motor that I replaced... The fact that I have good pressure and it holds for a minute means to me that I should at least get some sign of life when I crank it over... I took the battery out and put it on my charger over night as it was running down... I'm not sure what the Jeep ignition requirements are, but many others require at least 9.3 volts while cranking for the ignition to operate...The thing that has me puzzled the most is that there are no error codes being generated while trying to start it... Need to go put the battery back in and put a ounce of gas into the throttle body and see what happens... This thing has the coils directly over the spark plugs (i.e. no spark plug wires)... Is there a easy way to test for spark ??? Getting the coil pack assembly off the spark plugs is near impossible with the wiring connector still attached to it... Problem with that is it is in a near blind and very tight location between the coil pack bar and the firewall... If they had made the wires one inch longer it would be a piece of cake...

RTorrez1

Not always. I had 3 of them go bad on me on 3 out of the 4 XJ's I owned and they never throw a code for any of them. I also know of a few other guy's that had there CPS's go bad without any codes.

tjwalker

I agree with Robert. A failing crank sensor will set a code about 1 out of 3 times. These are called OBDII "escapes". The OBD system is decent, but there are many things that it will not pick up. MANY things.

Here is more on testing spark on the 00-01. Good luck!
----------------------------------------------------------
The coil design for the 00-01 is significantly different than that of the single coil and distributor setup on the earlier 4.0. You basically have three coils firing 6 plugs in the correct sequence, every crankshaft rotation (wasted spark design). This is an engineering departure from the older, single spark every other crankshaft rotation.

You can test the coil pack like you would the old single coil design, but its more technically involved than physically accessing the spark plug end. Because of the design of the coil rail, don’t test the coil rail one spark plug port at a time. Testing one port at a time causes the remaining coil ports to be free floating (ie, not properly grounded through the spark plug). Free floating an encapsulated coil secondary causes significant increases in the voltage induced in the secondary. This increased voltage can easily exceed the dielectric breakdown of the coil secondary and could cause the coil windings to arc internally and break down the insulation. If this happens, it has the effect of reducing coil energy delivery potential in the best cases and in the worst cases, causes the coil to fail. You need to install all 6 spark plugs to ensure you won’t damage the coil rail.

Because it is difficult to guarantee that you can correctly ground all 6 plugs at once, you should make up 6 separate jumper wires about 2 feet long. Pull the rail and flip it upside down. Insert 6 spark plugs into the rail. Attach one end of a jumper wire to the threaded part of the spark plug with a large mouth alligator clip and attach the other end of the jumper wire to engine ground. Once all 6 are hooked up this way, you can then perform your engine cranking test while observing spark on all 6 plugs.

EdZ

Thanks Rob and TJ... I like to test to find broken parts rather than throw money at the problem... I'll get a set of plugs for it tomorrow and see what I got for spark... If no spark then I will test (ohm out) the CPS and also see if it generates an AC pulse when the crank is rotated... Also need to verify the 5 volts present from the ECU to the CPS... Got some real nasty weather coming in this week, so if I don't get this thing going tomorrow, then it will have to wait till the weekend...
Thanks again for sharing your experiences ...

Ed

EdZ

As luck would have it, I put the battery back in and jsut for the heck of it I gave the key a twist to see how well it cranked over... Well, it fired right up and ran fine... So much for any further "valid" testing... Not a daily driver so it can let it sit for a few days and see if the problem returns... Does having the battery out for a day cause any program changes with the PCM ??? Only thing I can think that might be different from before when it wouldn't start...

BlueRidgeMark

Did you ever get this resolved? If so, can you give us an update?

I'd love to know if it was your CPS.

EdZ

Sorry for forgetting to wrap this one up... Turned out to be the battery... I am guessing that the removing of it and putting it on the charger helped it produce enough volts while cranking to fire the ignition... Might have been a bunch of sediment loose in the bottom of the battery case... When I put the battery on a load tester a few days later it failed miserably...

BimmerJeeper

No Start Checklist

NOT CRANKING

1. Check battery voltage (12V)
2. Clean/tighten battery terminals. (Loose and/or corroded?)
3. Check Gear Selector (Make sure you're in Park)
4. Neutral Safety Switch (Try to start in Neutral, not Park)
5. Check grounds
6. Is starter getting power? (With the key in the ON position, check for approximately full battery voltage at the starter.)
7. Starter (Hit with hammer)
8. Starter (Jump with screwdriver. Connect 2 highest bolts. 1 small. 1 big)
9. Starter Motor Fuse #19 (Kick panel: Fuse #19 (10A red))
10. Starter Motor Fuse #10 (Engine Bay Fuse Box (PDC). Fuse #10. See diagrams)
11. Starter Motor Relay (Engine Bay Fuse Box (PDC). “Cube” relay at end of fusebox)
12. Ignition Switch (Turn on the blower motor fan on for your heater with your key in the 'run' position. Turn the key to the 'start' position... the fan should turn off as it trys to crank over, indicating a good ignition switch.)

CRANKS, BUT NO START

1. Is gas tank empty?
2. Fuel pressure. 48psi (+/- 5psi). Listen for Fuel Pump?
3. Fuel pump relay (Engine Bay Fuse Box (PDC). Fuse #22. See diagrams)
4. Ignition fuse (Kick panel: Fuse #11 (20A))
5. Check for spark.
6. Bad spark plugs?
7. Bad Distributor, Cap, Wires?
8. Crank Position Sensor (CPS)
9. Bad coil pack?
10. Bad ECU?
11. Testing the TPS
12. IAC, TPS, CPK, MAP Failure Symptoms

Engine Bay Fuse Box (PDC)


Kick Panel Fusebox


Misc reading:
https://www.cherokeeforum.com/f2/non...writeup-71401/
https://www.cherokeeforum.com/f2/lon...8/#post2182489
http://www.jeepforum.com/forum/f11/p...l#post10006643
http://www.jeepforum.com/forum/f11/p...9/#post7683626
http://www.naxja.org/forum/showthread.php?t=101119
http://www.jeepforum.com/forum/f11/b.../#post14517948