loud noisy fuel tank

My 2001 D2 has a constant fairly loud whirring noise from the rear of the vehicle.. It doesn't sound like anything wrong its a healthy motor running whirring but its quite loud... at first i didn't think anything of it as it has been there since i got the vehicle early last week. but yesterday i traced the noise because i was worried it was the compressor constantly on.. it's not... it appears to be coming from the fuel tank on the drivers side.. so i assume its the fuel pump, should it be this noisy? is it an indication its on its way out, or could it be an aftermarket that just is loud, anyone experienced this that can shed some light..

Nige

Sounds like the fuel pump. Of you put the ignition to the on position but don' crank you will hear it for 20 secs and then it will stop.
They can be quite noisy, but they get worse before they break