'91 300CE - Fuel pressures (M104 engine)

[rgnprof]

Can anyone help here - I checked my fuel pressures today on my '91 300CE with the M104 motor and I get 3.4 bar with ignition on and car not running and 6.4 bar with car idling. Raising the rpm's does not change the fuel pressures at all...while idling, if I close off the ball valve on my gauges to the top chamber of the FD, pressure drops to 6.0 bar.

The only specs I can find are from FSM 07.3-0121 and they are for a M103 engine, and I'm not sure what they mean...sounds like 5.5 bar at idle...

I read a post by MBDoc indicating that it should be 3.5 bar at idle???

Thanks,
ryan