Dennis,
thank you for checking whether you could find such a blue connector in your car’s engine bay.
Yesterday, I checked the two purge valves of the charcoal canister and the purge valve to manifold with a hand-held vacuum pump and the valves were fine. I did not check the pressure reducing valve since I did not want to open the rusty T-piece and T-piece elbow fittings which are no longer available. I did not notice any smell of gasoline in the area.
I should receive the fuel pressure gauge within two weeks and then I can check fuel pressure and the fuel pressure regulator (FPR). I have sometimes noticed that there is slight smell of gasoline close to the FPR. However, I have disconnected the vacuum hose of the FPR and it did not smell. On Friday, I will go to an emission test in order to check the mixture. As I have said earlier the car runs smoothly and the fuel consumption is proper but the slightly rough idle bothers me still, even if I have checked and renewed lots of typical components and ruled out options. If the cause for the rough idle is not the FPR, then there are not many options left. Of course, there is the ECU. Next, I will clean the earth connections in the engine bay. Luckily, Don has provided nice instructions. https://forums.jag-lovers.com/t/xj40-grounds-earths-locations-identification-service-photos/286238
I sanded and painted the wiper arm and wiper arm nut cover. I used the same graphite grey paint I used for the windscreen cowl. Such small and immediate fixes improve the appearance of the car and make you feel good. I have also recently refurbished the original teardrop wheels using the method by Mercedessource. I have refurbished a set of MB wheels earlier, and this method really works. https://www.youtube.com/watch?v=PMEtayLG8os