Hi, I am Hungarian, sorry for the bad language skills!
I have a beautiful XJ S III 4.2 from 1979. While driving, sometimes the engine stalls and then stops. It never happened when the engine is idling, only while driving.
It will only continue to run if I switch the Fuel change over switch in time while the engine is stalling. No matter from which position to which position! Then it will run for 10 minutes or more without any stalling, then the trouble starts again.
I have already replaced the Fuel changeover valve but it has not helped.
Anyone have any ideas?
Thank you in advance!

My Jag

 

Beautiful Jaguar.

Personally, I'd begin with something very simple: replace the fuel filter.

Don't throw the old filter away. Empty the contents into a clean, clear container and then cut the filter open. What you see, or don't see, will dictate your next steps.

Cheers
DD

 

hello and welcome. you do have a very nice car. i know you are thinking some kind of furl delivery problem. fuel pump, maybe. fuel pressure regulator, maybe. if after you have ruled out a fuel delivery problem then may i suggest the ignition amplifier or the pick up coil inside the distributor cap. i recently was experiencing engine cut out while i was driving and it proved to be a bad pick up coil. i posted some actions i took while changing the pick up coil so you can search on my posts if you want to. hope they will help. good luck in tracking down your problem.

 

Hello Doug,
thank you, I will do it and we will see.
BR

 

Hello, thank you.
First of all I will check the fuel filter after Dough advice, and then yours step by step.
BR

 

Hello, what do you think, this unknown parts could cause the problem?

 

hi: i'm not sure what it is but it's a check valve of some sort for the fuel delivery system. i would not think that is the cause of you engine cut out while you are driving. did you searh this forum for engine stall out? there is also the forum jag-lovers.com.

 

Hi, not yet, but I will do it.
Now I recognise this burning by the connector of Fuel change over the switch, I will repair it and check the car. See photo.

 

Peter, congratulations on a truly beautiful Series 3! Truly a credit to you!
I was going to direct you yo check exactly that plag, I have seen it be the source of exactly the symptoms you describe many times. Also be aware, it can be the fuel changeover switch itself, losing contact internally. If you know of anyone from whom you can borrow a substitute switch, that is always a good way to exclude it from the symptoms list. This type of stalling is often caused by a momentary loss of power to the fuel pump (and subsequent loss of fuel pressure) due to a bad connection in that plug or the switch. I am confident you will find and fix it very soon - you are getting close! best wishes from Australia

 

Good discovery Peter. There is a very good chance this is the root cause of your problem. Are there any salvage yards in your area where you can get the harness (unless you think you can repair yours) and the switch itself?

 

Also posted over in the "Fuel Change Over Switch" heading.

Here is a pic of the zip ties holding the electrical connections together. As you know, poor electrical connections cause many bad and hard to find problems. Especially if they are intermittent. I made a career in the computer industry back in the day of second generation computers with printed circuit boards with the gold connectors. Pull card, clean connectors; problem go away.