Eugene,
you're touching on a moderately complicated part of the injection system now. First, your car should not have a fuel cut solenoid, those are only on later US-spec 280 SLs. It should have a cold start solenoid on the injection pump, though. Also the cold start valve on the intake manifold. These are controlled by the forward-most relay on the d/s inner fender. But it doesn't end there.
They are also controlled by either a thermo-switch, or thermo-time switch (depending on the year, they more or less the same thing, but one has a time cut-off and the other doesn't). At any rate, if the thermo-switch is bad, the solenoids won't operate even if the relay is good.
This whole system has been a favorite topic of discussion, so fire up the search function and start searching for things like "cold start valve", "CSV", cold start system, thermo-time switch, thermotime switch, TTS, cold start solenoid, cold start magnet, and any variations you run across in your wanderings. Study everything, there will be a quiz. Also, although the systems are generally similar, there are some detail differences between the 230 and 280 systems. Good luck and happy hunting.
George Davis
'69 280 SL Euro manual