I'm reposting my problem with my 90 300E that would not idle. Now it will not start. The problem is in the Fuel injection system. The car will fire on a small amount of starting fluid and die. The ICV shows zero volts on the harness. Should it show some voltage KOEO?

Some more background. The car use to idle low and rough when started cold. Once warm the idle would be smooth. Yesterday the A/C compressor would not engage. I drove home on the highway with no problem except the A/C not working. When I exited the highway and came to a stop the car died. It would restart if I opened the throttle slightly but it would not idle. Once I got moving the engine ran fine. Come to a stop it died. Today after the engine cooled, I can't get it to start. Can the OVP relay causes this? How can you test the OVP? Thanks for an input.

ICV at idle 600ma I believe.

So the next step is to find out why. I guess the ICV should have some power prior to start with the key on. Also there is no power to the ICV while cranking. Can other sensors to the ECU cause it to not "power up" the ICV?

Have you checked the OVP relay at all, the fuses on the top should be intact?

Check to see that the CIS system is recognizing electronic control. You can do this buy probing pin 3 of the x11 diag.port on the drivers side fender, or reading EHA current. At pin 3, you should see 69.9% duty cycle with the KOEO. At the EHA, you should see 20mA.

Without electronic control, there is no cold start enrichment and the engine will run crappy until warmed up. Hard to start as well.

__________________
'90 300SE 298k
-300K and it gets put into retirement.
'80 300D 255k Purchased new by family in 1980.

Had a:
1973 220 (gas)
1980 300SD
1992 400E

Thanks for giving me a direction to go for trouble shooting this anomaly. I have checked the OVP relay and the fuse is intact and the continuity is good. The relay clicks when powered.

I agree that the electronic portion of the fuel injection system is not working properly and I will conduct the checks on the x11 port. I have read from other threads that the duty cycle can be determined by certain multi meters from Sears. What feature does the meter need to measure duty cycle?

Assuming that the system is dead, is the most likely suspect the engine control unit?

Just found the Sear meter on a search. The Craftsman #82139 Sears #03482139000