M102 fuel pressure regulator question...
 

Can it be adjusted? I'm only getting 3 BAR working pressure... :(

I don't think it is adjustable. I'd try to isolate the fuel pump(s) and confirm its pressure output.

Is there any fuel leaking out of the small black vent hose that goes to the valve cover hose? Any fuel in that hose indicates a leaking diaphragm.

Also test the fuel accumulator for leakage. Pinch off the small rubber hose that's integral with the fuel supply hose from the tank, then remove the small hose from the FA nipple.

Attach a length of clear vinyl tubing to the FA nipple and into a container. Then turn on the ignition. This should energize the fuel pump for about one second. If the FA diaphragm is cracked you will see fuel run out the vinyl tube, which can prevent the fuel pumps from achieving design fuel pressure.

Run this test at least 3-5 times to be sure there is no leak.

You can find additional information on this by searching for threads started by me. In one I conducted a destructive failure analysis to determine the cause of the FA leak.

The symptoms I had was intermittent hard starting, both cold and hot that got progressively more common with time.

Duke