Any body help,my 110 200 tdi was losing power down to 10mph then speeding up then slowing down again I’ve just changed the fuel lift pump and put new

Just put a new fuel lift pump & fuel filter on my 200 tdi 110 as it was dropping power down to 10mph then picking up again then slowing right down just gone out in it tonight and it’s still the same managed to get it home never went above 20mph undone the bleed screw on top of filter nothing undone the banjo fitting on side of filter that feeds the filter nothing at all,when I manually pump it there is no resistance does it mean the new lift pump is faulty or some other reason.atb Ed

Could be a faulty lift pump, not uncommon these days. Or you may have installed it with operating arm wrong side of cam, also not uncommon.

They will run and drive okayish with a duff lift pump
I reckon you are drawing in air, either because your fuel gauge is lying or your pick up pipes have holes, maybe crud in the tank

Another vote here for the lift pump. If you have already replace what brand did you use? I use the delphi ones as I found other brands only lasted a couple of weeks, and even delphi brand will only last me a couple of years (all be it about 60k) before needing to be replaced.

that being said I would remove and check it is fitted correctly as above. Another thing you can do is eliminate the fuel tank and pipework. Sit a jerry can on the wing with a length of fuel hose in it and use gravity feed. You can then start with the feed to the injector pump straight into the jerry can and see if the engine runs and revs happily. If it does you can then move back an item one at a time to see where the problem is.

If you get your hands on a series 2 or 2a lift pump they can be refurbed. Repair kit's available.
The same pump was fitted to many vehicles back in the day so are still widely available.

Remember the cam needs to be in certain position to be able to prime it manually. Similar issue on my son's TDI was a split fuel pipe

Gauze on pick up pipe in tank could be clogged with muck ,either take out to clean or blow fuel hose back with compressor

I find a tdi will run OK with a bad lift pump but will be harder to start

Do not forget quite a few motors run the bosch inj pump with no extra lift pump, they rely entirely on the internal vane pump.
My point being, I think you are chasing the wrong thing.

Oh yes I remember another issue with some of the pumps. The olive (?) on the pipe into the pump don't seal very well and leak fuel out and air in (I presume) along the thread. My experience is that lift pumps will leak but still tend to pump well enough for the engine to work just fine. Leak off pipes have been a problem in the past and fuel filter gets blocked so changed every 6 months.

After running about for 2 weeks with new lift pump & fuel filter ok,had to be recovered by RAC last night same thing no revs but would tick over tried bleeding system today and bleed screw on fuel filter not showing any sign of diesel or air injectors bleeding ok could it be airlock in fuel filter. atb Ed

Take the fuel pipe off which goes into the filter and then see if the pump operates by hand. You need to start from the beginning and with the cheapest parts first.
Make sure all fuel lines are good, then lift pump and filter.
Once you are 100% on them then it's injection pump and injectors.
My son's 200tdi has a fuel cut off solenoid in the fuel line, no power to it means it will run but will not drive.
Also it very noticeable when the filter gets blocked, it will drive but no power to get up a hill.
Start at the tank and work forward.

All sorted now I removed the spacer on the new lift pump which was fitted to the old lift pump cut 1/2” off the 2 bolts to get the pump to fit flush and it’s now pumping as it should and filter bleed screw is working and running as it should. Thanks for all advice

I have never used that thick plastic spacer, you can get an Ali one which isn't as thick or take other advise and use three gaskets instead.
Hope it stays fixed this time.