1991 XJS 12cyl.
Still will not start. I have power to the coils and to the injectors but they will not pulse . Replaced Crank sensors and inertia switch. Fuel is functioning rear computer has been checked.
any Ideas. I have owned this car for 1 year and driven less than 12 times

Thanks

 

The Lucas computer has to receive a signal from the Marelli ECU in order to pulse the injectors. Seems to me, if nothing has changed, maybe the Marelli ECU would be the next thing to check before you spend another dime. The way I got my non running 89 going was help. Sent my Marelli ECU to a guy on another list, and even though my ECU turned out to be good, it let me know what NOT to look for. As it turns out, what finally made my car start, was filing the Boss(s) that both sensors mount into. I have a feeling that my car was out of spec from day one. What I did was measure the distance from the teeth on the flywheel to the rear "sensor" face, and it was about .045". I filed the boss until that distance was .020". I checked the front, and there are 3 fingers on the damper. The one with the most distance was about .047", and the one with the least was .037". I filed until the face of the "sensor" had .020" to the finger that had the least clearance. That made the one with the most clearance .030".
To complicate the issue, what I figured out is that the "sensors" are actually small magnetic pulse AC generators, or magnetos. They send a AC signal to the computer, and it in turn, sends this AC signal to the computer, and it uses that signal to tell the amps when to signal the coils. I had fire, but that fire wasn't timed right, because of the sensors.
Do you know the car has fuel pressure? I disconnected a fuel hose, and turned the switch on momentarily to see. Feel free to contact me and I will send you my number if there is any way I can help. Gene