Hi Simone.
Unplug it and disconnect the fuel line, then remove from the car so you can clean it up, once cleaned up give it a coat of black paint & re-fit.
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Scrap off all the blown rust.
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Use wire wheel to clean the rest.
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Do the same with the pump being careful round the in-let & outlet tube ends these should not be disturbed.
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Spray it or paint with Hamerite and fit it back to the car.
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The above should give to a rough idea