Lumpy Running and Flat Spot at 2500 revs

[philhunt]

My 1998 300 tdi has developed an occasional flat spot at 2500 revs. This occurs when driving along or in neutral but it's particularly noticeable in 2nd gear. It also feels lumpy at lower revs.

Only noticed it for the 1st time this morning  as I didn't get up to 2500 revs on Monday in the snow!.

May be a coincidence but everything seems to have been running fine until I filled the tank up to the brim with 60L a mile from home on Monday night in Tesco.

Fuel filter changed 5k miles ago. Diagnosis / ideas on fixing?

[300TDi Disco]

Does it go over 2500k??? What the injectors like??

[philhunt]

Sometimes whether in 2nd or 3rd it's fine and goes over 2500 revs but the flat spot seems to display itself more often than not in 2nd.

What should I be looking at with the injectors?

The engine has been running like a dream for the 2 years I've had it - although likely to be a coincidence, the problem has only occurred since I filled up on Monday night. Wondering whether an injector cleaner additive might be worthwhile and a filter change unless there's a pump problem or air getting into the system

[carracarra13]

Imust admit I dont tend to us tesco fuel any more as have had problems with there fuel  before (too much of a coicidence if you no what I mean)
but since Iv not used there fuel no problems

[300TDi Disco]

There was a big thing about tesco fuel a while back. I know it can sometimes be cheaper but i stopped using them, i just go to shell now. As much as it mite be a pain, use the fuel and get a next load in the tank and see what happens. A mate of mine has a disco 300tdi and that was had a pump problem which was making it run crappy.

[philhunt]

I've bought a new sedimentor in case I break the existing one when trying to clean'refurbish it. I've also bought a fuel lift pump and will replace the fuel filter. Fingers crossed it fixes the problem.

Anyone had a fuel injection pump go?