my '86 560sel's fuel pump is getting noisier. it's gone from a loud hiss to a whizzing sound (no it's not taking a pee!!)

is my fuel pump getting ready to quit?

also, parts site says it has TWO fuel pumps? are they both located under the car near the back right wheel?

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R Martin
Dallas, TX (Addison)

86 560SEL, 128K