I have a 1992 MB 190#, 2.3L. Recently we have been having a hard time starting it when the engine is cold. I have checked everything that most of the shops have told me to check, however, based on some earlier Volkswagen experience, my mind is made up that it is my cold start valve. All fuses are OK, with no corrosion, and the 10 amp blade fuse in the over-voltage protection relay is OK. I have disconnected the electrical plug to the valve and checked the connections. They are OK. I'm about ready to gamble and buy a cold start valve. ANy other simple checks that I should try. Any help would be appreciated.

You can unplug the cold start valve and check for voltage while cranking and with the engine cold. You should have battery voltage at the connector when starting and while running for a while.

If you don't have voltage, replace the over-voltage relay first, not just the fuse.

Interesting thing about cold start valves is that they don't do much in Florida. They only operate below 59 deg. Cold starting is almost never a cold start valve (in Florida anyway). I don't remember how accessable it is but I would unbolt it and pull it out of the manifold with the feed line attached and then try it cold. It should work for 1 to 12 seconds WHILE cranking depending how far below 59 degrees it is.

The first thing I would check would be the EHA current during starting (but I live in Florida). You should get 50-80ma current with the combined effect of starting enrichment (at all starts) and cold enrichment (varies with engine temp). If you have a bad OVP relay or fuse you will have zero, zip for current.