1991 Jaguar won't fire

My brother has a 1991 Jaguar XJS that won’t spark on either bank. I checked/tightened all grounds, charged the battery, and it fired- ran for 5 minutes. Now, it’s back to not starting; no pulse from the brain to the coils. Suggestions?

Since you say it won’t spark on either bank I’ll assume you’re dealing with a 12 cylinder engine. Since it’s a 12 cylinder it has 2 coils running on essentially completely diffrent circuits. If neither of them is producing a spark this would indicate a problem with the ignition switch, or the crankshaft or flywheel sensor, something like that.

Captain Jaguar’s Cathouse may be the best resource there is for Jaguar owners. Check this link for some extremely useful Jaguar service information.