Here's what my Mercedes factory manual gives for the 220Seb.
Electric fuel pump is tested with the engine off, a minimum of 11 volts at the pump and tank at last half full.
Fuel pump delivery pressure measured behind the fine fuel filter - 0.6-0.8 atm (8.8-11.8 psi)
Minimum delivery volume measured after return flow damper bowl - 1.0 litre in 15 seconds.

Spray pressure of used injection nozzles or valves.
Minimum - 13.0 atm (191 psi)

Happy Motoring, Mark

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DrDKW