Car ran fine when I parked it. Sat for a month or so. Tried to start it and battery was dead. charged battery in car. Used fast charge and slow charge. Battery charged is now 75%+ charged. Car cranks fine now but wont run. Pulled a plug and grounded it to the engine while connected to coil. No spark. Any suggestions? Thanks.

 

There are three black relays at the right front corner of the engine bay. The one closest to the windscreen washer reservoir is the Engine Management System relay: swap it with one of the other two relays next to it.

That's the first and easiest thing to try, the most likely is that the Crankshaft Position Sensor has failed. It's mounted on the timing cover, passenger's side, and points down at the crankshaft pulley.

Without knowing the level of your testing equipment and ability, that's as far as I'm going for now. You did a good job to this point, and checking for injector clicking when cranking will be helpful too. No injector pulse+ no spark, and I'm hanging a crank sensor on the car instead of wasting any time... that will probably end the story.

Here's a scarier one, and an example of a possibility that isn't so easy to find: I met a guy through here who towed his '97 XJ6 to my shop two Sundays ago. Nice kid, nice car but it had been bumped in the nose and been sitting for quite a long time. The EMS relay was intermittant, but the relay was fine: I could fire the engine when I substituted the ECM ground at the relay, and it would still run when I removed the jumper wire. Going to the ECM, I removed the connectors and found them full of water, and corroded. Pin #18 is the ground signal to the EMS relay, and it was almost completely gone.

Only point is that it isn't always easy, hopefully yours is. jag_genius had posted once about seeing this problem, this is the first I had seen it and I don't know how common the water ingress is. Post what you find, I'll help if I can.

 

Thanks, for the reply.
I swapped the relays (all 3), still no go.
When I pulled the plug it was dry.
I listened to a couple of the fuel injectors with a stethoscope but no clicking.
I used my scan tool (CanOBD2) and got a code: P1791.
The scan tool manufacturers website says the definition of P1791 is: "Throttle position electrical signal failure".
It bothers me to read that, and makes me think something big is going on here.
May be something was "cooked" from charging?
That would be a first for me, but none the less I am apprehensive because it happened just after charging the battery.
As for my tools and experience, well I have worked on many cars but never a Jaguar until now.
They just never came across my lift.
I no longer work professionally on cars.
My tools range from crude hammers from the stone age to oscilloscopes, but of course I don't have everything.
The CanOBD2 scan tool wasn't my first choice, but my Snap-on scanner didn't (and apparently never will) scan Jaguars.
I don't have any Jaguar specific tools.
My only manual came with the car (I am not the original owner).
It's an "Original Edition Publications" in CDROM format and sadly only works in a Windows arena.
It's almost a useless manual.
For whatever reason it skipped that code.
So, to summarize, Crank Position Sensor?
Can I test it?
The CPS is easy enough to swap out, BUT
it's a fairly big ticket to just swap out and find it didn't fix the problem.
Thanks again for helping me out and please pardon my ignorance.

 

Throttle position code is new information, and can fail so as to inhibit injector operation but you would still have spark. Throttle position sensor shorts, ECM thinks the throttle is wide open and doesn't sigal injector pulse. You can litteraly reach under the throttle body and disconnect the TPS connector, and the car will start...IF it has spark, that is.
The TPS fault will not inhibit ignition.

With everything assembled, crank the engine and watch the tach. By your details, it should not move at all. If ignition is working, you'll see 200 RPM.

I bench tested a good used crank position sensor at 1300 ohms. I don't know for sure if a sensor that roughly matches that resistance necessarily means it is sending signal.
Most often CPS failure does not generate a code.

 

I disconnected the TPS (Throttle Potentiometer) did not run.
While cranking tachometer showed no movement.

 

No, it wasn't going to run with the TPS disconnected because you have no spark, which is why your tach doesn't move, which is because your crank position sensor is bad.

 

Ok, I changed out the CPS with a new one.
Still no fire and no movement of the tachometer.
Has 1/2 tank of good gasoline.
Tried it with the TPS disconnected and got nothing.
More suggestions?

 

It won't take much to inspect the ECM connections: pull the RF footwell RH side trim panel, unbolt the ECM, remove the two connectors from the top and have a look. Beyond that, you need a wiring diagram.

 

I agree. Unfortunately my manual has terrible schematics and I am not looking forward to hunting through the wires for the problem, but what must be done must be done. Do you know of a way to test the ECM besides (yikes) substitution?

 

Did you inspect the connections to the ECM yet?

 

No, later today I will and see what is going on. The CPS didn't come till' late yesterday afternoon so I haven't had the time to look yet. Hopefully it will just pop out at me an be an easy fix but I am still skeptical. We'll see... I'll post what I find then also.

 

Right side fuse box in engine bay, fuse F6 is a 5a fuse for power to the EMS relay. Also check #11 (20a) and #12 (10a), although I think either of these would inhibit cranking.
The relay in that fusebox is for ignition, try swapping it with an identically numbered one in the trunk fuse box.