XJ40 drove well last outing. 2 months later battery was flat 6 V .Charged up battery & car would not fire. Have fuel at rail, have spark, have compression. Starter just winds over then sometimes when turn key off motor kicks backwards. Have changed plugs, ignition amplifier. Cannot move car to get it to garage as unable to get tow truck up hill.Car is under house and has not been wet. Have checked 3 fuse boxes all O.K. Have put aerostart in airflow system and no kick at all when turning motor over. Wayne

SOURCE: motor

I had the same problem. The dealership wanted to charge me $12,000.00. I told them where they could go...The problem with my engine (I also found out this is common with this style,year,whatever) the timing chain busted...NOT the timing belt, but the chain inside. I had the engine rebuilt.

SOURCE: wont start, no faults on ecu,keeps flooding,

Sounds like the old nikasil problem.Remove all of the spark plugs and squirt oil down each bore,replace plugs and she should fire up.

SOURCE: car wont start

It sounds like this could be a common problem - usually this is caused by the crank sensor going out/bad. The sensor is mounted to the timing cover on the front of the engine.
The crankshaft sensor provides both engine speed and crankshaft position signals to the ECM. The sensor is a variable reluctance device, consisting of a bobbin coil with a magnetic core. The resistance of the coil is approximately 1.35 kilo ohms . The steel teeth on the crankshaft timing ring are used as a rotor. As the rotor teeth pass by the crankshaft sensor, pulses are generated.

The rotor has 60 tooth positions set at 6° intervals with three teeth missing. The gaps identify the TDC position of the 6 cylinders during one complete engine cycle (two crankshaft revolutions). The rotor thus provides both engine speed and crankshaft position information to the ECM. The missing pulses identify crankshaft position. Each tooth pulse after the missing pulse represents 6° of crankshaft rotation. Thus the frequency of the toothed pulses are a measure of engine speed.

SOURCE: 95 xj6 , have electrical power starter does not work.

On most car batery"s there is corrosion, on Jaguar,you don't see it. Take off neg- post cable first than pos, and clean posts and cables with a battery. post cleaner. kgb

SOURCE: 2001 Jaguar S-type won't start

Check if your transmission really is in park. I once had the same problem and it was fixed by moving the stick in and out of the park stand for a couple of times. Then the red light illuminating the "P" came on and i could start again.

Has to do with the transmission cable that tends to get a bit loose.