200 injector pump problem

Hi all.
I got me a little problem. I have an 'L' reg 200 tdi disco (no thats not the problem). I have just put a new injector pump on it as the other one was nackered. So this 'new to me' (second hand) injector pump has been played with before i got it. I know that as it goes like stink. My old 200 has never gone that fast! Anyway on top end and through the gears its fine, in face its better than fine, but when its been on tick over for a few minutes ie: at the lights, it dont want to play ball. You loose all power. By that i mean you can put your foot hard down and you get nothing at all, only tick over. After a litle pumping of the gas it comes back, only 5/10 seconds and its ok. The tick over is all over the place, is goes from almost stalling to 11/1200 rpm. When you stop it then restart it the motor will tick over all day.
So a new lift pump was fitted (i know this is to only help on start up, but for what they cost) then the bowle at the fuel tank was cleaned out, then a new diesel filter was fitted. Still the same.
Can anyone please help me. Please dont tell me that i have to get another pump. Its not the cost of the pump that bothers me to much (50 quid) its the time fitting the dam thing, and we are of up to Scotland next week in the old girl.
Thanks for all that you can give
Paul @ Doncaster

The injection pump has its own vane pump built in, and there is a pressure regulating valve that keeps pressure up inside. If you have the valve then it may need cleaning/adjusting, very early ones without full flow fuel will have a bleed port and are not affected.

I haven't got a picture of 'your' pump in front of me, just working on a generic DPA/DPS pump.

If the pressure drops away, then you're not going to have enough fuel to full the pumping element. Once the rev's are up, the pump is OK and has enough pressure to do the job.

First thing I would check.

Peter

It sounds like the metering valve is sticking,Bosch VE pumps tend to break up internally with old age/water/rubbish going through them.
A good way to check is to remove the stop solenoid and look inside it,any flecks of swarf tell the story.