Hopefully the video might provide some clues, could the starter be going bad?
http://web.mac.com/mark.beazley/iWeb/Site/560SL.html
Alright, the 560SL has become very hard to start when cold. recently it has also become harder to start when warm. I have noticed if I dribble water on the injectors the one in cylinder 3 will cause the engine to bog down some, indicating a leaky injector. I am posting a video of a typical start up to hopefully get some ideas of what else I should be checking for.
Actions taken: The battery fuel filter and coolant temp sensor are brand new, The pump was replaced last year. I have cleaned the Idle control valve. I could not find any vacuum leaks, but it does run worse when it rains. I have cleaned the fuel distributor.
Symptoms: extremely difficult to start when cold. If shut down and restarted when warm will fire right up. the longer it sits the more difficult it is to start. When Cold, idle hunts from about 1100 to 500 RPMs. When the engine temp reaches around 82 degrees it settles down to about 750-800 RPM at idle. When warm running above 40 MPH the engine will occasionally enter a pattern of power loss. (like a draw on the engine lasting 2 seconds then back to normal for 2 seconds, pattern repeats for about 45 seconds then goes away) Things I have noticed: then starter will occasionally drop in pitch and speed as though it is under a heavier load, you can hear it in the video. When this happens the car is more likely to start. I can also hear what sounds like a relay clicking in the passenger footwell and can hear what sounds like fuel sloshing around in the tank while trying to start. I never noticed it before, but I wasn’t listening so It may be normal.
I would appreciate any advice you may have.
Thank you