I am having a similar problem with my 86 740 GLE. My first thought was fuel, as there was very little in the tank. I added a couple of gallons and found that I am getting fuel to the rail and into the cylinders. So checked the spark. Nothing. Checked the coil and still no spark. Read a whole bunch of posts on this and traced things to the power stage / ign. amp. As one of the posts suggested, I check for power at the plug to the power stage and am getting the appropriate power at the plug. So I figure it is the power stage that is shot. I realize that a new one should be better than a used one. Does anyone have any idea how much one is?

Also, just in case, where is the Hall sensor and how does one test it? How much are they worth?

I don't want to spend a whole lot on this car as I got it real cheap and only want a daily driver for the summer. But I have to get it to start before it can be even considered a driver of any sort.