I have a 230 sl which has an R11 pump and is initially presenting as a cold start issue first start of the day is a little slow to get going and will predictably run for 2 seconds first crank, the proceed to die and on second crank will run beautifully and go through the full warm up cycle without hesitation. after testing every piece of the cold start system nothing seems to be at fault I even checked my fuel pump check valves which seem to be in working order as it seemed to be a fuel delivery issue, the caveat to the story is the longer it sits the worse the start up becomes, after a weekend it will run on 3-4 cylinders and die multiple times until finally finding a happy running condition. I am suspicious of the injection pump itself and the possibility of fuel in the injection lines dissipating into the oil system however I cannot smell fuel in the oil so hesitant to condemn the pump.
any info tips or tests to confirm a leaky pump or knowledge on the typical conditions of the pump and injection lines at rest is greatly appreciated. I am rather versed in Mercedes Benz cars so don't be afraid to lay it all out!