Just aquired a beautiful '89 300SE with only 63k. When starting the car cold or prior to full operating temp, we have to keep light pressure on the accelerator to get it start first time. Car runs great once started and, currently, has no other running issues. I believe I have a cold start valve issue. What does the collective wisdom of the Forum suggest? Am I on the right track?
dws

 

First off, 63K...thatsnice. Not much wisdom here but I have a '91 300SE that I love and I've had the same issue you're experiencing since I became the second owner of mine in '07. I say same issue but I've found that if I just hold the key in the ignition position the car will eventually start. Regardless of outside temperature. Then if I cut it off directly after starting the car the first time it will then start like turning on a light each successive attempt without fail. I have asked several "experts" about this issue and I've been told that's just the way it is. I may have started a thread here about this very thing. Additionally, when I checked the car's manual sure enough it said that you may need to hold the key in the ignition position "for up to 4 seconds" for the car to start.

Again, you have said you may need to depress the accelerator but you should double check that you actually need to do this in order for the car to start. All of this said if you find or have found a cold start fix please post it up.

 

look at the fuel pressure accumulator, near the fuel filter. I had a problem with my 280se as the accumulator was broken. It keeps a head of fuel pressure available for start up. If this is broken it takes a few seconds to build up fuel pressure for it to start.
hope this helps