Rare occurrence on Monday, the old bus refused to start and of course I was at a remote fishing hole 20 miles from home without my phone …only option was hitch-hiking and luckily someone took pity on an old fool with oily thumbs 
so I managed to get home.
Had car towed into town next morning and fearing the worst (fuel pump AGAIN argggh!) was happy to see plenty of fuel squirt when I undid the rail connection. Checked spark and had spark too but a bit on the orangey side …so unless a python had crawled up the air intake, I had air too.
My mechanic mate was confused as to why she wouldn’t fire up, but I remembered a thread from a while back about a non-starting car that the owner replaced just about every ignition component trying to get it to start …and last of all replacing the ROTOR …
Yes lads, the rotor on the XJ40 relies on an epoxy potted resistor for the connection from the centre to the end - and that resistor breaks down.
I had a spare (old) rotor in my parts stash and swapped it. My mate was on the phone when I cranked the car which IMMEDIATELY fired up and the look on my mate’s face was priceless!
The car had some lumpy idles on initial starts for the last little while that I now know was the rotor breaking down. With the replacement, she starts better and runs more sweetly - and I believe has more power too.
So first thing I did last night was order a new rotor that will live alongside the spare CPS and hopefully prevent me ever having to hitch-hike again!
Thanks for your story. My 73,000 mile 1990 XJ6 stalled in an empty parking lot two weeks ago. Cranked fine but would not start. Had it flatbedded (first time in 30 years the car has had the “ride of shame”) on my classic car insurance policy to my very experienced British car shop only 2 miles away. Learned later in the day the fuel pump that I had them replace as preventative maintenance not 1500 miles and 2 years ago ago had failed. They fitted a new Bosch one, filter and relay and I was back in business. They covered the repair due to the premature failure. While I was waiting for the flat bed since the only thing a non technician with no tools can do is pop off the distributor cap and have a look. Contact points, and rotor tip looked a bit rough so I later ordered new ones which I fitted myself. Carrying the displaced ones in the boot in case of a failure.
Larry, I’m glad the problem was that simple. I assume when you got into the person’s car who picked you up, you didn’t see any chainsaw anywhere, right?
I also learned my lesson a few months ago when the engine just cut off while driving (about 25 mph). Since then I got a new cap and rotor that I keep in the trunk.
Found this on the web, interesting …
The rotor resistor was an early attempt at radio noise suppression. Same role as the resistance in spark plug wires and the spark plugs. No other reason. The resistor actually causes the secondary side voltage to rise slightly higher by a few percent before spark breakdown so the voltage overshoot is higher. Without the resistor there is less voltage stress on the coil, distributor cap, rotor, and spark plug wires. In addition, once spark breakdown does occur that added resistance will reduce the spark energy due to the current limiting it provides. For CDI use, the resistor should be removed and replaced with a piece of wire, or eventually the higher power of a CDI will cause the resistor to go open-circuit” - Contributed - Frederick C. Winterburn