Car recently pulled out of seasonal storage, couldn't move shifter at that time. Rotary switch on transmission shift lever was seized due to internal corrosion binding the internal contact wiper. Dismantled switch, removed corrosion, resealed/ reassembled. Another problem soon developed due to possible internal contact contamination resulting in it only cranking in neutral-after rocking shifter back & forth a few times. Anyhow, could drive car until it died on the road soon after. Had to get it hauled home, where it sits. No restart, it sometimes tries but won't stay running.
Troubleshooting sequence as a result of VCM fuel fail code 24( ignition amplifier) :
power to fuel pump relay- OK.
relay click when attempting to start-OK.
disconnect fuel rail, check fuel pumping- got fuel moving.
proceeding to ignition, coil ok.
distributor cap/ rotor clean & dry.
12 volts to ignition amplifier plug with ignition on, got it.
ignition coil output, definitely there.
I'm currently against the wall on this one, could the transmission switch be part of the problem? Haven't reassembled & reinstalled it yet. Are there any other faults besides a faulty ignition amplifier that could cause this thing to act this way, & is it possible to test the amplifier while off the connector? Anyone with knowledge who may be able to home in on the possible cause(s) of not starting & staying running would be my hero, being without "Bigkitty" is no fun! Thanks for reading such a long post, I try to be as informative as I can when asking for help.

 

I've moved your question from General Tech Help to XJ40 forum. Members with the same model are more likely to see it here.

Graham

 

The only thing that has ever stopped my car in its tracks was the breakdown of the rotor. There is a component potted into the rotor designed to aid in radio suppression which bridges the connection from the centre to the tip.
This component can fail and develop high resistance resulting in a very weak (orange) or non-existent spark at the plugs.

Of course this may not be your issue. Just another FYI for your toolbox. BTW, I assume you have a reading on the tach while cranking?

 

Thanks for reply! An update: I replaced the fuel filter yesterday after several days of soaking the fittings with penetrant oil & several hours of effort in removal. This car is supposed to have slip-connect fittings according to Haynes manual, but has standard threaded couplers.
old filter was hard to blow air through. I got it started afterwards ( she was most reluctant) but after achieving smooth idle it eventually stalled & couldn't restart.
fuel fail 24 code indicative of failing ignition amp, or could something else upstream from the amp, like the ECU faulty, I'm wondering, along with the possibility of testing the ignition amp via DVM or resistance check? Meanwhile I shall examine the distributor rotor, although when I checked, spark was good out of the coil.
WAY too much electronics in these cars!

 

Nothing to see, good one looks like a failed one. You should check your spark at the PLUGS and it should be strong blue not yellow/orange.

 

when I last did that, it was looking a bit weak, but I need to recheck when dark or close to it, when I can borrow a neighbor again to twist the key while I'm under the hood. Thanks for the advice!

 

after reading this, I yanked the rotor for a resistance check, resulting in a 9 k ohm reading. Look about right for a suppressor unit?
Update: I reinstalled rotor, started car (after cranking for a short time with no resulting run - duh! Forgot to reconnect coil wire! Fixed that, car's now been running fine for about 15-20 minutes or so, all systems appear as normal. I'm hesitant to take it down the road without an escort for fear of it stalling again & not restarting. Aaah, what to do? I need this thing back in action - for my mental health!

 

A couple of things I have had happen that you may have fixed inadvertently- Is it possible the coil wire was not seated completely to cause the problem? Also I had a distributor cap with a bad/ weak spring under the center button. The button got stuck up inside the cap and wasn't making contact to the plug terminals. Good Luck.

 

Partial success- removed ign amp/ plate for a clean-up, there's a ground wire connected to it that upon removal was looking rather lame, along with an externally- mounted capacitor connected between coil (+) post & coil mount bracket. Ampohm 1uF 150 volt marked, looks similar to the condenser in a points ignition system. Physically & electrically compromised so out with it, it's not shown on any of the schematics I have anyway.
Cleaned all connections, dist. cap & rotor look (test) good. Reassembled all, it starts & stays running now. Coincidence, maybe. Next mission is to try salvaging shift cable, binding in housing since I acquired the car. Previously lubed from inside car, worked for a few years but is getting rough again. No n.o.s. replacements I've found yet, used are from $300 + up where available. Also awaiting new fuel pressure regulator, I've long suspected its faulty due to long cold cranking to start, although when cool Temps prevail it often fires upon just touching the key. Projects, projects. Add to that r & r drivers door handle & inside lever return spring...

 

Update: after new fuel pressure regulatory & filter, no start/ intermittent restart no change. I got to troubleshooting fuel delivery system. Fuel pump relay good, power to pump via relay good. Must be fuel pump, can't hear it running when it should be. First project I've had to farm out re: this car, as I've no frame lift to facilitate the ALLEGED need to remove left rear drive line to access fuel tank connections. My Volvo mechanic was able to get super- long needlenose pliers up in there to get fittings off the tank to remove from car. Fuel pump motor had commutator worn clear through the copper segments right into the plastic below. I'm surprised that it ran as long as it did. Would've been nice if Jaguar had thought to provide fuel pump access from inside the car, but noooo!