As owner of a 230SL I recently experienced more and more starting problems (hot and cold) . Checked all the relays, thermo /time switches and electrical connections in the entire starting circuit.
They were all fine, so the problem seems to be on the fuel side.
After removing the tiny shut off valve and grub screw on top of the unit I tried to blow air through the nozzles. They seem to be clogged.
I removed the nozzleholder using a vice. Clamping the nozzleholder in the vice and gently turning and pulling the CSV housing does the trick (thanks for the tip dr Benz !)
The nozzles are difficult to clean . I used a cheap ultrasone cleaner filled with cleaning vinegar ( letting it soak overnight might work as well) and poking carefully with a needle and using compressed air. It opened up both nozzles.
To check the spray pattern I connected a lenght of tubing to the nozzleholder, sucked it full with water and then attached a blowgun. Keep the tubing filled with water.
Now be carefull ! Use only relatively LOW airpressure when blowing out the water and checking the spray pattern , otherwise your nozzles might go into orbit around mother earth when pulling the trigger on your blowgun !
In my case the test was succesfull. so I installed the nozzleholder again ,this time using the vice as a press.
Again I tried to blow air through the nozzles from the outside ,but no luck.
After removing the valve actuator /relay you'll be able to see a small part of the tube which holds the nozzles on the other end. Close examination learns that there is a small hole in it (see photo) . This small hole is often overlooked and starting problems might persist . When the actuator presses the valve open on starting , fuel enters the via this small hole in the tube to the nozzles . In my case this hole was clogged as well ,so no fuel was getting to the nozzles during starting.
I opened up the hole with a bent paperclip and now finally fuel was getting to the nozzles and the CSV should be working fine again.
