Overheating, overboosting, black smoke! Urgh!

[wurlycorner]

Yep, swapping of the fuel pump in the process has to be prime question mark over why it's now over-fuelling (black smoke).
Do you still have the original Lucas fuel pump? Was it still working?
If so, might be worth swapping back to that and see what it's like then.

[Pug_XUD_KeenAmateur]

PS: dead giveaway if the Thermostat's stuck closed.... the Rad will remain cold despite the engine temp

[Stewart(oily)]

On my S2 Xantia, late 1.9 td the fans did not kick in until 95 degrees, I was used to my BX fans chiming at 88 degrees and until I realised I was pulling the brown connector off the thermostat housing to force the fans, I only found out when on a busy motorway I watched the temp climb to 95 and then they kicked in.