I have noticed during the last few days that when my 1997 W210 is hot, it is a little balky to start on the first try. When cold, I don't have a problem. The car runs and idles fine.

I have searched the forum for ideas and come up with the crank position/reference sensor or a valve/regulator in the fuel rail. To elaborate, the problem does act like a mild flooding. If I step on the accelerator just a little when it occurs, it seems to eliminate the need to turn off the ignition and try again at which time it always seems to catch and start. I have no CEL but have not checked for codes with my scanner.

What info/advice can you folks share?

Can somebody tell me if the CPS can be changed on this model from the open hood?

Fuelpressure regulator ( mounted on the fuelrail ) looks like this:
http://img.eautopartscatalog.com/live/thumb/C300053377BOS.JPG
Pull the vacuumline off & smell or " taste " the inside of the vacuumline.
Any sign of gasoline means it's leaking.

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2007 C 230 Sport.

Had the same problem a couple months ago. Was solved by new fuel pressure regulator, as the diaphragm in the old one was likely shot. I got mine for about $60 from eBay. Took about 5 minutes to replace. You can check the existing FPR by removing the vacuum line and smelling/checking for the presence of fuel (it should be dry and not smell of fuel). I tried this on mine, and it had a faint fuel smell. The kicker was when I did this and started the car, my FPR was trickling fuel. I'm sure with the vacuum hose attached it was probalby sucking large amounts of fuel into the intake, causing the "flooding" behavior. You might want to look into this.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

off of the fuel pressure regulator and found a small amount of gasoline there. Will order a new one. Thanks for the input guys.

The flooding isn't helped by the fuel leaking through the diaphragm, but that isn't the cause of the rich condition. Without the diaphragm intact, the fuel pressure regulator will see a lower pressure than actually exists. Thus the pressure at the injectors will be too high, and the computer will be injecting more fuel than it computes is needed.

Thanks for the explanation. I've been trying to figure that one out. It didn't seem like the small trickle would be enough to create the "flooded" condition, but when added to what you described it makes more sense.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

fuel pressure regulator installed this AM. Problem not evident after that. Thanks for the lead.