380SL - What does a "fuel pressure dampener" actually do?
 

This is a follow up to my thread on mixture control problems on a '85 380SL.

http://www.peachparts.com/shopforum/showthread.php?t=201524

I am trying to figure out why the lambda system appears to work, but actually does not.

Looking at the plumbing for the frequency valve, it goes like this:

- Upper chamber of fuel dist
- to frequency valve
- to "fuel pressure dampener" on side of mixture contol unit
- to another dampener behind the mixture control unit
- to lower chamber of FD

The dampeners are connected to vacuum in the upper intake manifold, which means they should get vacuum when the throttle is opened.

My suspicion is that one/both is/are malfunctioning and preventing the lambda system from changing the pressure in the FD.

Understanding what they are supposed to do would be a big help. They must do something important - Mercedes invested some very elaborate plumbing to put them there!

Picture of dampener attached.

To cut down on fuel "knocking" noises(waves) that can damage the fuel distributor.