Cold Start Difficulty

[wahoo]

Having lots of trouble cold starting my 1965 230 SL.  Runs fine once started.  It has a Bosch R28Y mech fuel injection unit paired with a 280 SE engine.  However, the solenoid on the back of the pump is currently not wired to anything.  Is this the injection starting solenoid?  What should it be wired to? 

[Shvegel]

On the later pumps like your's the single solenoid is for fuel cut off as part of the emission control system.  The system is designed to shut the fuel off when you are coasting so it is OK that it is unplugged.  Cold start issues can "usually" be traced to low fuel pressure/flow at the fuel pump or an inoperative cold start injection system.  If I was diagnosing it I would remove the small hex head screw on the cold start injector hold a cup under the hole and have someone crank the engine and see if fuel comes out for aproximatly 7 seconds.  However, in the interest of safety get ahold of a 12 volt test light and connect it across the 2 terminals of the cold start injector.  Have someone crank the cold engine and see if the light lights for about 7 seconds.  If that checks out then you will need to check fuel pressure and volume. I believe the specifications for the fuel pump are in our Technical Manual section.

[wahoo]

Thanks very much.  I will leave the solenoid as is.  The issue seems to have been a faulty wire to the CSV.  I rewired it yesterday and it started right up.  However, it ran very rich for too long so I suspect the CSV isn't shutting off properly.  Will pull the CSV and clean it then check the time switch relay. 

[Shvegel]

If you remove the small hex head bolt on the side of the cold start valve with the engine running there should be no fuel coming out of there.  Hold a cup under to catch any drips.  the bolt is downstream of the valve so if it isn't leaking you don't have to pull it apart. 

[ja17]

Check to see if your CSV is automatically getting power during cold starts first. After this check we can move on to the other possibilities.