are you sure it stops as it shouldnt or is it that its just excessively noisy to begin with till air is purged,it might be worth checking the filters in pump housing ,then move onto other causes
It should stop after 30 seconds if the engine isn't started. But it does sound as though you have problems as suggested.
FUEL DELIVERY SYSTEM - TD5 - DESCRIPTION AND OPERATION 19-1-11 said:Operation
When the ignition switch is moved to position II, the fuel pump relay in the engine compartment fusebox is energised
by the ECM. Battery voltage is supplied from the fuel pump relay to the fuel pump which operates. If engine cranking
is not detected by the ECM within a three minute period, the ECM will 'time-out', de-energising the fuel pump relay.
When the ignition is turned off the ECM timer will reset.....
i hate to contradict people but i must... cos it's important to be accurate on these things... it's not about 30 seconds, it's around 3 minutes, that's why the purging sequence takes the same