I understand what you are saying.

What i am describing is a process of elimination on the fuel supply side.

If each segment of the flow path can be checked from the tank to the injector, then there's no uncertainty in the fuel delivery... The engine doesn't have to be running only cranking fast enogh to check for "normal" operation of the fuel delivery system.

If there is no fuel to the inlet of the lift pump then something is wrong with the tank,tank screen or hard fuel lines... if there is no low pressure fuel reaching the inlet of the IP then there is something wrong with the lift pump or filters... if there is no high pressure fuel reaching the injectors then there is something wrong with the IP. Pretty easy to eliminate in that order.

If the diesel won't start and the GPs and Starter are doing what they are s'posed to be doing then there's either no fuel or the compression is gone.

If it were me i would treat it as if it had been run dry of fuel and work through priming the fuel up to the injectors before i did any repeated cranking or spraying anything in the intake.

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"