Hello everyone, this is my first post on here, and I hope I can get some help.

I have a beautiful 2000 Jaguar Vanden Plan with about 125k miles on it. It had never left me stranded until last December, when the original almost 25-year-old alternator went out on it. My dad and I are handy enough and ordered a rebuilt one from RockAuto and replaced it. It worked great until about a month ago, when it was showing signs of going out: battery light, battery not charging, accessories not working, etc. So I parked it and had the alternator tested, and it failed. By the time my dad and I got another alternator from RockAuto and installed it, it had been 2 weeks of the car not starting or running. As soon as we installed the new alternator, we tried starting the Jag up, and all it would do was crank.

Currently, all the Jag does is crank despite the battery being good, fuel pump is good, spark plugs seem to be good, immobilizer seems to be working, and I have my doubts that all 8 injectors have stopped working, but I haven't tested them yet. Despite the alternator going out, I had no other issues as far as running and driving excellent. My dad and I were getting good fuel pressure at the fuel rails, so that ruled out the fuel pump. The spark plugs we tested came back good. I think the immobilizer is working and recognizing the key because when I set off the panic alarm and then insert the key, it stops. Have yet to test the injectors, but I suspect that even if half of them spontaneously went out, I would still be able to start the Jag but have a misfire. There have also been no codes. All ground wires seem good, and anything removed to replace the alternator was put back correctly.

I hope someone can give some advice, and thanks to anyone who reads this and gives advice.

 

As a first step, I'd recommend to take 3 voltage measurements with a multi-meter:

1. with ignition off.
2. with ignition on, but not in start position
3. while cranking

...and try to remember, if you could have disconnected somewhere an electric cable (or even a vacuum tube) while swapping the alternator, which you then forgot to connect again...
If you disconnected the throttle body motor and did not reconnect it, that would cause the problem at hand. I don't know off hand, where that is on the X308, but on the S-Type it is hidden under the big black rubber hose between air-filter-box and throttle body and therefore it is easily being forgotten, as it is out of sight.

 

does it have spark

does it have injector pulse


only thing you need to know

 

I was taught in high school shop class, If you work on your car, and it does not start then go back and fix what you did.

 

And then there's those of us who are not foolish enough - or simply don't have the right tools or equipment - to do any more than describe the symptoms and hope we were accurate enough to have our mechanics try to fix them.

In high school I think it was called "Putting Your Mechanic's Children Through School 101" and it has many societal benefits in addition to keeping us from screwing things up even more while trying to keep our cars on the road.

 

Quick test, crank while someone squirts starter fluid. If fires fuel, if not spark.

 

Thank you for the advice. I don't recall there being any vacuum lines near my alternator, but I will double-check the area. I will also do the voltage measurements.

 

Spark seems to be a yes, but I will be checking injectors soon. Thank you.

 

That is something my dad and I tried, but idk if he sprayed enough starter fluid. Thanks.