76 450 SL air flapper position

[Benz124s]

Hi Everyone,
I'm working on getting a 76 450 SL running again. I've searched already for this particular question but couldn't find anything. I'm wondering where the air flapper is supposed to sit when the car is off. Mine stays open a few mm. The car will start and run for a second or two then dies. I measured control pressure to be around 4.5 bar and when I close the valve on the test gauge the pressure only slightly rises. I have the electric connector disconnected on the WUR. Also I have a rebuilt fuel distributor from Flowtech and clean non ethanol gas in the tank. Return line to the tank is also clear. So does the position of the flap make a difference if it keeps running?
Thanks!
Dave