200Tdi No power White Smoke

Driving back from uni earlier today, suddenly I completely lost power even putting my foot to the floor. I managed to turn into a side road just as the engine cut out and lost power steering.

The engine restarted but was very lumpy and when revved white smoke poured out and then cut out again. I disconnected the inlet pipes which made no difference so the problem isn't with the air supply. Cracking the bleed screw on the fuel filter while running initially didn't spill any fuel so I can only assume that it wasn't full? Pumping the lever on the lift pump a few times with the screw open and then restarting it seemed to do the trick. I managed to do the 6 miles home without any problems.

Why would the engine suddenly stop like that and then run perfectly again? Could it be an intermittent fault with the lift pump?

Sounds like fuel starvation cause by a blockage, might have something floating around in the tank which got sucked in to the pick up pipe and blocked the fuel supply. When the engine stopped then the suction would stop and allow it to fall away. A duff lift pump shouldn't stop a running engine.

Well worth the effort of removing the little round cover of the front of the timing chest (3 screws) and then move the crank a little each way just to check all the belt and the crank woodruff key are still good, 5 min job start to finish.
Used to be common and made a mess of the crank, dont seem to hear of it nowadays.
Ive had a few lift pump die on a 200 and all it does is lack a little power at the top end.

Did the white smoke smell of paraffin?
If so, it is generally down to over-fuelling caused, maybe by a blocked air inlet or a timing issue, which allows unburnt fuel to exhaust.
Obviously, many would immediately jump to the conclusion that your head gasket has gone, but, as you say you got home with no problems that would probably rule that out.
Personally, I would start with the air intake, and go on from there.

Any further news on this mate?

sounds like the fuel line may have got blocked somehow and then a load of it was released in one go, once - sort of - unblocked, hence the white smoke

the purging via the lift pump might have shifted whatever was there, hence the return to normal performance.

still worth checking the cam belt and turbo though but also maybe a new fuel filter?

I've ruled out an intake blockage as I tried it without the inlet pipe connected to the inlet manifold and made no difference. I rebuilt the engine around 1000 miles ago and had a new fuel filter 400 miles ago. Seems to me like it was a blockage as I took it for a short drive today and seemed to be fine. When I get the chance I'll try and clean the tank out and blast some air down the pipes.

Tank has a drain bung on the bottom so maybe worth draining it down when its low on fuel and see what you get?