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.

You need to determine if it's ignition or fuel.

If you pull the coil wire off the bottom of the dist cap, and place it near the firewall or some other ground source, do you get a good spark when turning the engine over?

If yes, you get a good steady blue spark, then lets look at the fuel system, or possibly secondary ignition: wires, cap, rotor, plugs. Any or all of those things can cause no-start; they should all be in good condition. How do the plugs look? How does the cap look? A just-washed engine often won't run due to water in the distributor cap. It's happened to me...

If spark is absent, then you can look at the coil, the ignition module, and the hall sensor. In these cars, no ignition trigger means no fuel pumps being turned on, that's the way the ECU and fuel relay work. Has to get the signal from the ignition system. Again checking for spark with the coil wire off is a good clue- if there's only ONE spark as you turn the key off, then it's not being triggered. Hall sensors are notorious on these cars; yours is overdue if original. I replaced my wife's 88 distributor over 3 years ago because of this.

It's also VERY likely to have a failure in the fuel pump relay. Try a new one, or a known good one that works in another car. One from any 85+ 240, any 740 or 760, or any 940 will work fine. PN is 3523608.

Beyond that,you'll have to see if the main pump runs; then pull off a fuel line and see if it's actually delivering fuel to the fuel rail.

Good luck!
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Rob Bareiss, New London CT ::: Roterande Fläkt Och Drivremmar!