Ok so I have a problem with my fuel pressure regulator for sure. Rebuilt my solex 4a1 and when I put it back on fuel was pouring out of the carb. So I thought it was toast. I actually had a brand new 2bbl autolite laying around so I converted it over But same problem. So I am positive its not needle and seat problems. My question is.. Is there an upgrade? I am guessing you need one because I ommited the regulator and same problem. So that means the fuel pump is pushing out to much pressure for the needle and seat to properly seal. But exactly how much pressure do these put out?

As I do have a universal pressure regulator I can set anywhere from 1 to 6 psi (I'm guessing 3 is what you need) but it can't handle over 7psi inlet pressure and does not have a return. So can this be used or do I need a genuine merc one with return? A work around or upgrade existing?

A M110 with a carburettor has a mechanical fuel pump, not electric.

The pressure is very low, needle valves are not designed for the pressure of an electric fuel pump.

Rob

I have an M110.981 in a 280CE (W114) , D-jetronic. I know this is not carburettor engine, but it may help. My fuel pressure is 2.1 bar, and drops to 1.5 bar when engine is off. These are the correct settings for my car.
I know, because I had a faulty fuel pressure regulator, and had to set correctly when replacing with a good one.

Q