A couple months ago I rebuilt the aluminum fuel head on my '87 930.
It was spraying fuel out of the #4 injector continuously if the pumps were running even if the motor was off and the metering plate was at rest in the middle of the AFM housing venturi cone. It would idle and run on 5 cylinders up to around 2000rpm when under low load because #4 was way too rich.
After replacing all the o-rings on the control plunger cylinder and the rubber diaphragm from a $69 Salvox rebuild kit off ebay the car runs perfectly smooth all the time.
The o-rings and diaphragm from the Salvox kit are ethanol tolerant and the ones that were in the fuel head were not.
A couple weeks ago I rebuilt a cast iron fuel head. I followed the instructions on the Salvox site and watched you tube videos people have made while rebuilding Mercedes fuel heads.
