I have aquired a 1989 xjs in pretty good shape problem is there is no no fire, what all will cause this. ecu? crank sensor? coil? is there more that will cause no spark. Please help..

 

Yes to all of the above, and plenty more potential causes for no spark.

Just to be clear, the problem is confirmed to be no spark ? (ie you have confirmed you have fuel at the rail and under pressure, and that there is indeed no spark on ANY of the plugs ?)

Whats the history of the car ? Did you buy it not running ? or did it run when you bought it but now its not running or ?

Does the car have Marelli ignition ? (You can tell this by looking at the distributor cap and seeing if it has 2 coil leads going into the centre of it (instead of the previous lucas system which only had one)

 

i got the car not running. there is fuel. its defenitley no spark. it has two coils on it(cap has two) i really want the v12 to run and prefer no v8 swap as my dad suggests. my coils show hot on the test light but i dont know what they should read on the volt meter. but i understand there multiple reasons for no spark on this car is why im trying to figure out where to look. and what about trying to find a wiring harness that goes to the coils i fixed mine was too bad but i only fixed cause i broke it oops

 

Sounds like you have Marelli ignition.

You have two coils, two control modules, two crank sensors, and an ignition "computer"...the ignition ECU.

A couple easy things to look before before you get into a lot of testing:

1) Pull the dist cap and inspect the rotor. It might be burned or show signs of arcing. Common problem.

2) If you have no spark AND no fuel injector pulse at the same time, you almost positively have a crank sensor problem. Most guys replace both cranks sensors ar once if that scenario...about $65 each or so.

A "noid" light is the best way to check if the injectors are pulsing but you can also just listen for the characteristic clicking...use a long screwdriver held up to your ear or get a $7.00 mechanics stethoscope.

Cheers
DD

 

Thanks for all the input I will check it out. Where is the crank sensor located? where can i buy them. And what are the module looking things on the front nose of the car that is on the same harness as the coils? Im trying to learn all i can and its very hard finding this information on the net and on the forums prolly just havent found the right spot yet so the search continues.

 

so the things on the front or the control module, still havent got to check anything my other thing is just where to buy parts from

 

You can buy crank sensors from any Jag specialist---Coventry West, Motorcars Ltd, etc or even from Rock Auto or Parts Geek. It might be a good idea to establish a relationship with a Jag parts specialist (such as mentioned above). Sometimes it helps having a human being to work with versus an on-line vendor.


There's one at the front of the engine just below the crank pulley and another at the rear by the flywheel. They're about the size of a .45 slug with a couple wires attached.

The ignition modules are the two sorta sqaure-ish boxes above the radiator

Cheers
DD