Update: Well gentlemen, the engine started today, albeit with a whiff of ether and a few dribbles of gasoline. She woke up about as well as a teenager that was out late partying, but she did wake up, that is until all that I had fed it was consumed. Apparently, injection is not working. With the schrader valve depressed it blew gasoline up to the ceiling when the key was turned but I didn't have a gage to measure pressure at that moment. Before it started and during cranking, it backfired, likely due to less than stochiometric air/fuel ratio. When it did, I saw smoke come from the throttle body as one would expect, but there was also a significant jet of smoke toward the port side coming from under the plastic intake plenum near the front of the engine. I have to assume that will be a significant vacuum leak, but the engine did run quite smoothly and apparently on all 8 for as long as the fuel lasted. Next session, I will remove the plenum and find the leak, unless,, you guys have any more magical solutions. Are there any common problems here I should be aware of?

 

I would expect it to settle after a bit, maybe try to run it again for longer?
If fuel pressure is too high you will have to address it before digging any deeper, you either have blocked fuel return or faulty fpr, after that you can test for air leaks in an usual manner and the chance is there are none

 

So then, how do you account for the smoke under the front of the organ pipes?

 

it could be excessive back pressure due to backfire, once everything goes back to normal there may be none of it

 

Is there some sort of blow off plate under there as seen on my supercharged engine?

 

Nope, if your observation is correct and smoke came from under the plenum then it must be from the manifold seals or at most from the throttle body, air assisted tb has extra pipe connecting it to ...me thinks... valve covers, make sure you didn't miss anything installing tb

 

Connection to the throttle body were 2 electrical connectors, 2 coolant hoses and 1 unknown hose with a sepcialized 90 degree plastic fitting that simply plugged into the throttle body and a throttle cable. I repeated the startup several times and saw this happen each time. Now I have seen these plastic organ pipe manifold/plenums warp and/or crack on other cars. Lincoln Town Car comes to mind, so that is what I'm suspecting right now, but I'm hoping its just a failed seal.

 

i suppose it is normal that normally sealing seals would give under extreme pressure of backfire that's why test and fix the fuel first, your tb sounds just right

 

OK, I'm getting back to the VP project now. I ran the engine on ether squirts a couple times and it didn't backfire and sounded very good. I measured about 36 psi on the fuel rail but no luck continuously running the engine on gasoline. My first inclination was to check the ECM power/fuse/electrical connection(s) and wiring. In my effort to do that, I found no less than 5 fuse boxes scattered around the car. That must be some kind of record! And not one of them had labels identifying the fuses, just numbers. Nothing inside the lids and no section on fuses in the owners manual. Even Grok couldn't tell me where the ECM fuse(s) are. It tried but it told me it was fuse #13 in the larger fuse box under the hood, but it turned out that one was the horn circuit. Even Google's AI had this to say;

"AI Overview

The 2000 Jaguar Vanden Plas has a primary Engine Control Module (ECM) battery fuse located in the engine compartment fuse box, which is situated above the battery on the driver's side of the engine bay. Refer to the fuse diagram on the lid of the power distribution center (fuse box) to pinpoint the exact location and amperage of the ECM fuse.

Locating the Fuse:

1. Open the hood: of your vehicle.
2. Locate the battery: in the engine compartment.
3. Find the fuse box: on the driver's side, directly above the battery, covered by a black plastic lid.
4. Remove the lid: to access the fuses and relays.
5. Consult the fuse diagram: on the inside of the lid to identify the specific fuse for the ECM. "

However, the battery is not under the hood, it is in the trunk/boot. There is a fuse panel near it, but the cover is missing.
I'm scratching my head raw on this car. It has more fuses than an airliner, and for what? How many circuits can it possibly have? And Jaguar must hold each one's identity as a closely guarded secret. The owner's manual doesn't even show 'fuses' in its index. That's a first for me. Got any ideas?

 

Yeah, this lid is pretty useful, i would get one in a junkyard for future reference

 

.

 

Thank you for the image Jack. And, thankfully, there is another XJ8 in the bone yard. That is where I got the throttle body and the hood leaper. As I removed it from the engine which was haphazardly dropped onto the windshield and cowl after removing the trans, I wondered if this was yet another case of a car being unjustifiably scrapped due to loss of compression that could be so easily remedied. I will go back there and get a few more items including the fuse box cover.

This car continues to cause me wonder. As I sit behind the wheel, I realize that I won't be seeing any large people exiting these cars, It is barely big enough for me. and I am of very average build at 5'10". The interior has little room to move around and headroom is quite limited. Ingress and egress are a challenge for someone with legs. For such a big car, at least by European standards, the interior is disproportionately small. It has microcephaly! And the one thing I really appreciated about these cars was the dual gassholes, and now there is just one, it remains a beautifully sculpted car with very nice appointments. All that said, I think I'd rather see the straight six from the sixties under the hood instead of this fragile Ford V8. As I wrench on this car, I can't help wondering how much more fun it would be with this 454 under, and over the hood. But then I get real and realize that it is simply too much fun in the boat. If Jaguar had built a boat, It would have been just like this. There is not enough room under the dash to bend my knees, there is no windscreen on an 80 mph boat. The supercharger pully is perfectly located to remove hair from back seat riders. The transom has freeboard such that waves are invited into the engine bay, and the battery is located under the foredeck where only a very small yet strong monkey can access it. That said, it is at once, the most beautiful, yet useless boat in existence. It sucks a lot of fuel, makes a LOT of noise, and the only thing it's good for is picking up chicks!

;

 

The fuse diagram was only installed in the 1998 cars here in North America.
The 1999 onward has just a blank black lid.(the fuse diagrams are not all the same on later cars)

 

The fuses can be identified by following the schematics in the Electrical Guide, which can be downloaded at our member Gus's website, jagrepair.com. It's a bit tedious and not as convenient as a chart, but any fuse can be identified along with the fuse box in which it is located and its fuse number.

Cheers,

Don

 

Thanks Don, I downloaded it, it looks a bit con-fuse-ing but I think I'll get through it if I need to. Hopefully the fuse chart Jack posted will do the trick.

 

It's NOT a Ford engine. It's a Jaguar engine.
It's an old wives tale that just won't die.
.
.
.

 

Didn't Ford own Jaguar during the time of that engine's development? Why did it appear in the Lincoln LS? I understand that Ford was "helping" Jaguar cut corners and save money, hence the reliability issues.

 

jaguar begged to not have the modular shoved in and dearborn said ok and let them design their own engine. every aj in a jaguar was built by ford workers in the bridgend plant

when they codeveloped the dew98 platform it was designed around the aj. dearborn just decided and build another casting and assembly line with extra space in the lima plant instead of importing them.