I have an 85 325e BMW and I can hear the fuel pump humming, which pump could it be? External or Internal?

I be more concerned if I did not here it. You hear it humming you know that it is working. When the late time you changed the fuel filters? It make the pump work harder. Most like you're hear the both. But out one is to the hard work of pushing the fuel through the filter. There may be another filter located by the fuel tank. It the one no one re[laces.

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