1990 Jaguar XJ6 Car stop running

Check for " sure" you have fuel to the fuel rail. If not check fuel pump. You should be able to hear it run for a few seconds when you turn the key to run.
If not, check the fuel pump relay located below the glove box. Test for in/out voltage when you turn the key to run.
Check to be sure you have spark. You can do this by pulling any spark plug wire and inserting a phillips head screwdriver into the boot, laying it on the valve cover and cranking the engine. Spark should jump from the driver shaft to the valve cover. If not, check the ignition relay, same location, like you did the FP relay. If neither relay i/o voltage, check the main relay, same location. This relay supplies both F pump and ign. Relays.