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

A control pressure of 4.5 bar, even with a heated WUR, would be too high. Without heating the control pressure should not exceed ~ 1.5-2.0 bar.
Control pressure that approaches system pressure is likely to be caused either by internal blockage of fuel flow in the WUR, or by blockage in the fuel lines going to and from the WUR.

Thanks Frank. I'm taking apart the warm up regulator today to try and clean it. Does anyone know where I can find a new gasket for the two halves of the housing that contains the air flap?