Hi,
Welcome!
We have an 88 300 TE in the family, which is pretty similar...

Fuel pump relay is on the passenger side of the engine bay against the firewall... behind the battery... under a plastic shield... next to or behind the one that says Clima on it.
Fuel pumps... yes there should be two.... one is under a simple plastic shield BEHIND the rear axle shaft, next to the gas tank.
The second one is under a simulated floor panel, passender side forward of the axle. the fuel filter is here also.
Thats about all I can help you with.

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2009 Mercedes ML320 Bluetec