I just got a 76 450SL, was not running, replaced the Fuel Pump Car Starts now. However it will not start unless with the Key in the Ignition turned far right (not starter engaged) and pressing down on the air diaphragm to let fuel into the injectors for 10 sec or so to get 'The screeching sound' then I can crank the engine and it will start, runs up a bit rough for a min or so till I press the gas down and get revs up then it smooth’s out and idles and runs great.

With those symptoms’ and further reading I took apart my Warm Up Regulator and soaked it in gas, used some compressed air through the 2 fuel lines (not the small vac diaphragm though). and reassembled it. It did not make any difference. However today in looking at some Drawings of the WUR's I see there appears to be a "Rod' or "Pin" (see pic) between the Top inside where the Fuel Enters the WUR Chamber and the top of the Cone that sits over the Spring. Mine did not have any "Rod" or "Pin" as illustrated. Just the 2 Springs The Cone and Thermal Element. Should there be a "Rod" or "Pin' between the Cone and the Top Inside of where the Fuel is delivered? See Red Arrow on my attachment.

Any advise what else I should look at or for? Air Temp Sensor?

I am considering purchasing the Unwired Unit, it looks like a nice reliable improvement.. allthough budget is limited.

Thanks,

Scott