I have a 1996 XJ6. The following has happened 3 or 4 times in the three years I've owned it. At first I blamed the battery, but I've replaced it and it still happens. Here's the scenario: I have multiple cars. Sometimes I need to move the Jag out of the way in the driveway. I'll start the car (cold), move it a few feet and shut it off. The next time I try to start it, even if less than a minute later, it will crank very slowly and not start. It's as if the battery were dead, but I know it isn't. When this happens, sometimes it's days before it'll crank fast enough to start again, even if I try charging the battery in the meanwhile.

Has anyone else experienced anything like this? I'm puzzled.

 

My 1991 Mercury Grand Marquis would do that when hot and stopped for short duration....like stopping at the grocery store for a few items on the way home from work...never happened cold...until the very last time...and I always got a start even though it barely turned over. One fine morning (cold-start) it wouldn't hit a lick, and naturally, I'd parked it astraddle of a landscape timber on the edge of the driveway the evening previous....so no access whatsover to the starter motor... after a failed jumpstart attempt or two, the youngest lad and I winched it up to the shop using chocks and a come-a-long and swapped out the starter: no further problems.

The major problem with that in your case is not so much that your symptoms are markedly different (even though they are!) as that one fixing bolt on the X300 starter is reportedly a real (bit-ter ex-wife) to remove and replace. Hope you find the problem.
Good luck and keep us posted.

 

possible that the replacement battery may be weak too?

 

Thanks for the responses guys. 96X300, if I recall, I've also tried jumping the car while it's in this state, with no success, so I'm pretty well convinced it's not the battery. But thanks for the suggestion.

Aholbro1, I HAVE removed my starter (another issue, and a LONG story). It's everything they say it is. There are two bolts holding it in. If you look at it from underneath, one of them is staring you in the face; the other is impossible to see. I first conferred with a mechanic at a Jag dealership and he gave me the news - to remove the starter you first have to remove the intake manifold to get at the top bolt. What he neglected to mention was that to remove the intake manifold, you essentially have to unwire the entire engine compartment, as the wiring harness runs between two of the intake runners.

I did all this last winter. I usually keep the Jag off the road for a few months in the winter, to avoid the road salt. Last year, after it had been sitting for a few weeks, I went to start it (just to let it run a bit) and NOTHING. Turned out it was the Body Processing Module, but in the course of troubleshooting this I took the starter out and cleaned up all the contacts. But I ramble ...

Anyway, thanks again, both.

 

Mmmm, back in the day when we had 8 Jags, and a single width driveway, much moving of Jags was required from time to time. I NEVER started any of them and shut them down as you described, just not in my brain, I left it/them run, and many were V12's, so engine flooding was a real issue, especially the PreHE ones, damn I miss that, NOT, HAHAHAHA.

My X300 has a hissy moment if my "old brain" forgets and does what you do, but it does crank normally, just gets bitchy about firing.

I would seriously look at the +ve battery lead connector, and the associated "buzz bar" attachments of that connection, they can reek havoc at the weirdest times.

The other connections would be the earths, but you may have covered that with the starter issues I think.

The AJ16 EFI system delivers ONE squirt of fuel into the cylinders each time the ignition is switched ON, prior to cranking, hence the NO NO of shutting down until it is at least "warmed up", my opinion on that one, and NOT Jaguar specific.

Under the bonnet are +ve battery posts, so I would be checking them as well, coz on the earlier cars they were known to loosen and cause cranking issues.

The starter relay may be getting lazy, they do not last forever, but failure is NOT a real common complaint.

Maybe more, but thats a start.