Starting Puzzle

[jammer]

Hello All,

1989 300SEL with 130k. This issue has been puzzling me for a while. The car stumbles for about a minute after a slightly hard start first thing in the morning after it was driven the day before. Sometimes it doesn’t start with the initial crank. This also happens with a warm start. So temperature doesn’t seem to be the cause of the problem. However, when the car is parked for a couple of days (over a weekend) or longer, it fires right away with the first crank and idles fine with no lumpiness of hesitation. What could be the culprit? I am thinking Fuel Accumulator/Fuel Tank Vent Valve simply because of the time factor involved. What is/are the function(s) of the Fuel Accumulator and the Fuel Tank Vent Valve?

Thanks