I think I'll need a new fuel pump soon....

Annoying isn't it, you take off in 1st gear with WOT, drop the clutch then repeat the same in 2nd gear only to find the boost drops off and the revs won't go any higher before suddenly coming back again. Not only that, but some times the car 'splutters' on a start and, as MRP will testify, will try and start and then 'die' straight away especially after a long run (the fuel pump probably gets 'hot').

Now, this problem has been around prior to the refurb on my Turbo and I'm almost certain my fuel pump is getting weak. When I open the throttle fully (in 1st and 2nd particularly) it obviously demands a lot of fuel flow, then when the pump can't manage to push that much fuel through, the ECU intervenes and cuts the boost until the fuel flow has caught up and hence the drop in power. If the fuel pump is becoming weak and the tank is getting low it will have problems pushing fuel as there is less 'weight' behind it so the pump has to work harder. Might explain the occasional start-up issue as well.

Considering I've got refurbed injectors and turbo, a TCV/BCS from Volvo that's only around 12 months old, no obvious splits in my vacuum lines (another possibility of course) and no split hoses or pipes (as far as I can tell), it's a fairly safe bet that the fuel pump has seen better days.

Before I consider a remap or rolling road session I think I'll change the fuel pump and sender units (my fuel gauge doesn't work as some will recall), and then go from there. Preferably new ones as well of course, other than that some quality low mileage second hand parts will be ok and Bridgend Volvo Specialsts will be doing the work for me because one slight issue with that plastic 'O' ring and I'll have a massive fuel leak (been there, done that, got the T-Shirt).