B230 engine won't start. LH 2.4 Jetronic fuel injection. Ran rough idle for the final run then crapped out for the last time about a month ago. Since then I've discovered there is no pulse to the fuel injectors. I have an '89 240 with the same engine/injection - minor differences - and have swapped out everything imaginable: ECU, ICU, injectors, rpm sensor, etc. But have not found the culprit. The injectors have + power on them, just no pulse! The Code 1 Diagonostics show a healthy ECU: 1-1-1. My mechanic has worked on the car also for many hours and is stumped. It's not the radio suppression relay, not the fuel pumps, there's spark, there's fuel pressure; everything looks just perfect! Signals into the ECU look correct. I've looked at wiring harnesses and they look very clean and almost new. The car is well maintained; the engine is nearly spotless: 87k miles total. I believe the problem is something to do with the RPM sensor SIGNAL. The RPM sensor is good. Is it possible that the sensor is good but the sensor ain't getting a "pulse" from the flywheel? How would one check this without an oscilloscope? What could cause this condition?

One tidbit: the car started and ran for about ten seocnds after I swapped my 240 ICU into the 740; then it wouldn't start. Jeez.

A related question regarding error codes: I went through the diagnostics and do not understand how to get the "RPM sensor signal" code. The FAQ says the following:
"Install the cable into socket 2 for fuel injection-related tests.
Press the button two times for >1 and <3 seconds each. The LED lamp should flash.
Activate the following sensors...(goes through steps for the TPS then...)
RPM sensor signal from ignition OK 3-3-1
...Exit Mode 2 by switching off the ignition."
How does one "activate" the RPM sensor to get the signal? crank engine?

I've checked harnesses but I could've missed a crucial junction. Any suggestions in this area?

I'm really bothered by this. The car stopped starting four days after I bought it. The seller is a friend and coworker and he's embarrassed but tacitly feeling lucky. I paid him $2500 for the 740; at the time it was a good and fair price.

Thanks in advance. This is a GREAT website.
Don Lewis