I read though a bunch of threads already about similar problems, but none seem to be exactly the same as mine.

First off the car is an 1988 300E. It has been garaged for a few years with a bad transmission. This year I decided to get it back on the road so I replaced the transmission and out it came. When I parked it, it did not have any starting issues but a had already replaced the Fuel Pump Relay once.

Since I have been driving it again it was very hard to start (much worse the colder it was outside) and started stalling again while driving down the road. I once again bit the bullet and bought another Fuel Pump Relay and the stalling stopped, but not the cold start issue.

Now the car is hard to start even when it's relatively warm outside 50-60F and takes a bit of feathering the throttle to get it going. Once it reaches operating temp it runs great. and starts right up again as long as the engine still has some heat in it. A couple mornings last week were quite cold and the problem was compounded getting it to start. But again, once about 60-80C engine temp was reached it ran perfect.

I believe it is one of 3 possible problems, but rather than guessing which is the problem I'm hoping someone can help.

As I see it, it could be (1) the OVP relay, (2) the Cold Start Valve or (3) Coolant Temp Sensor.

I read in a post to unplug the CTS directly after starting the car to see if the engine behavior changes (Stalls, RPM's climb..etc), so I did and nothing changed at all. I did this a couple time and it did not make any difference in the engine's behavior. It seems to me that the CTS may just be the problem but at better than $100.00 I was hoping to get other opinions.

I do have an Ohm meter, just not sure what resistance I should be looking for at the components.

Any help would be greatly appreciated.

Thanks,

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Ron D.
-2007 C230-
-1998 ML320-
-1988 300E-