I parked my manual 1990 240 at the airport (a stone's throw from seawater) and when I returned a week later it would not start. It will crank just fine but won't start. Did some troubleshooting and found no spark at the plug, and no spark from the coil/distributer lead when held close to a ground and cranked.

Cleaned up distributer contacts, replaced the coil, replaced the lead from the coil to the distributer as a precaution - still nothing. The coil gets about 13.6v with the ignition switch on.

Checked the power stage (amplifier) inputs. It gets battery voltage, but it did not seem to get the 0-2 volt fluctuation the Haynes manual said to look for while cranking. I'm not sure the digital multimeter we were using would even show that oscillation acurately, so I tried replacing the power stage - still no spark.

The next thing Haynes says to do is have the ECU diagnosed. I'm not ready to do that yet. Besides, wouldn't it be the ICU that would need tested?

I checked for diagnostic codes for both Jetronic (2) and EZ-116K (6) and got no codes. Not even the 1-1-1 which is supposed to signal "no codes detected". The red LED would light up when I pushed the button, but it never flashed. This worries me although I suspect it is due to having the battery disconnected numerous times.

Other potential clues - In the couple of weeks prior to the no start, the car stalled out while decelerating and shifting into neutral approaching a red light. This happened twice, but not a consistant phenomenon. Also lately the speedometer has been really wacky, and on occaision the temp guage doesn't work. Whether or not the sensors which signal to these guages are tied into the ICU or ECU is something I have been unable to determine conclusively. The posotive lead to the battery was really corroded, so I cleaned it up. A lot of the metal on one side is gone, but seems there is still a really solid connection.
Also, I suspect the check engine light has been out possibly for a while now (doesn't come on when ignition is on).

The next thing I want to take a hard look at is the engine speed sensor, but it doesn't seem like something that would tend to just fail while the car is parked. Then again the same goes for all the other things I have checked.

Here's what I want to know(aside from exactly how to fix the problem);

1) Would a bad fuel pump relay stop the spark?

2) Would a bad engine speed sensor/wiring stop the spark

3) Would a bad coolant temp sensor/wiring stop the spark (Haynes says to check this)?

4) Should I be concerned that the self-diagnostic unit doesn't flash the 1-1-1?

5) Is a Bentley manual any more informative than the Haynes?

If anyone can contribute some info I'd be grateful.