Cold Start solenoid system

[LJHAMILTON]

My 1966 Mercedes 230SL cold start system is having a problem when the engine is warm and you shut it off and restart it, it floods out.  We have to hold the throttle to the floor to get it to clean out and start.  Any suggestions on fixing? Thanks for your help.

[Peter]

Most probably the “thermo switch” is broken.
It is opening the CSV also when the engine is warm, starting becomes then very difficult.

Testing procedure see: https://www.sl113.org/wiki/Restricted/Engine-starting-aid-tour

^Peter 

[wwheeler]

Has it always done this or is this a new phenomenon? I assume it runs ok after it starts? An easy way to test before doing the more in depth investigation is to simply disconnect the CSV solenoid electrically and see if it helps. You can do the same for the starting solenoid. If it is not connected electrically, it won't activate. That will tell you if the solenoids are flooding by activating when they should not.   

[ja17]

Good advice from wwheeler.  In addition you may want to make sure your check valve on the return circuit of your injection pump is not stuck. If so fuel will not circulate back to the fuel tank and may just heat up and vapor lock causing difficult hot starting. Always make sure you have a clean and adequate fuel supply, check the filters and screens, check the fuel pressure and volume. W113 cars used four different starting systems depending on the date of manufacture. Your 230SL could be equipped with version II, or version III. With version II, your engine will have a "thermo switch" and a "thermo time switch". The "thermo switch" not used after version II. Most 230SL engines have the check valve built into the banjo fitting on the top, front of the IP. The return line to the tank is hooked to it. Make sure the slide valve with spring is not stuck. Determine if your engine uses version II or III (most likely III). Do your checks and tests. Research the systems as described on this site. Get back with us with more information and questions!