2004 SL600 M275 no fuel pressure

[Roncallo]

I have a friend with a 2004 SL600 M275 engine. He came back from a car wash 11 months ago, the next day the car would not start.

I looked at it and the car had no fuel pressure.

We put a volt meter on the pump connector and observed ~ 11.5V at the connector. Battery voltage for both batteries was ~12.5 and 12.8

Replaced fuel pump no change.

Could not figure out why the filter had 4 ports so we disconnected it and plumbed the FP right to the pressure gauge. Zero

Did replace the fuel controller with a used??? one no change.

My understanding is that this may use a PWM fuel regulator and in that case 12V measured at the connector may be meaningless.

I have limited access to WIS and STAR but don't really know how to use it well.

I did successfully confirm that the driver authorization system is in start mode.