The fuel pump is audible and should run with the key in the on position.
I have been able to get a vehicle with bad fuel pump started by smiting the bottom of the tank with a rubber mallet while someone else cranked the engine. Note that this should be used only to start it and drive it immediately a short distance to the mechanic. Or if you are going to DIY it can be a way to confirm that the fuel pump is indeed bad. Of course if the kinetic therapy doesn't work it doesn't confirm that the fuel pump is not bad so other diagnostics are a good idea.

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1983 M-B 240D-Gone too.
1976 M-B 300D-Departed.

"Good" is the worst enemy of "Great".