My 1978 XJS V12 Jaguar

My jag had a small engine fire through air cleaner - catching wiring on fire, I have replaced injector harness, engine harness (all with genuine jag parts) distributor trigger unit, fitted fast ignition system from USA
The injectors will click while turning over throttle pulley, but no pulse while cranking motor the ignition has spark and timimg is correct have tried another ECU but no luck - had a jag mechanic who put a wire from battery to the ECU don’t know where but it ran - he said he could only do it 3 times
Mechanic has now moved on - I need help with this please can you help
Regards - Colin

1978 means D Jetronic, which means trigger board under the distributor cap. Is yours the original mechanical reed switches (3 wires) or the upgraded Hall effect unit (4 wires)?

It also might help to post a photo of your distributor rotor. It has to have a magnet in the tail, but the configuration of the rotor for the 3-wire trigger board is reportedly different than the configuration of the rotor for the 4-wire unit.

I have misc. parts from a 76 and 78 XJ-S I dismantled. Let me know what you need. I may have it in a box in my storage facilities.


Tried replying by email - yes the trigger board and rotor are upgraded “Hall Effect” with 4 wires I followed the instructions for fitting (3 pin plug and extra wire that is spliced to S.W. on the ballast)
The ignition is the shutter type “Fast” (trade mark USA -
Regards Colin
Hope this helps to solve my problem

You say you have spark, you say the injectors click when rotating the throttle turntable, but there’s no injection when turning the engine over. AFAIK, there are only three things that can cause that problem:

  1. No signal from trigger board in distributor;

  2. Wiring between trigger board and ECU is bad; or

  3. ECU is fupped.

I’m not sure how to narrow it down any more than that. Perhaps someone else here can chime in.