What ? a problem that can? be also bound to the catalyst of a challenge... if any ? with that car, since I don't know for sure. The pump, if I'm not mistaken ? a normal bosch classic press with the only electronic actuator, type VW golf 110cv to speak, and a part of the actuator that you put the new pump in ? rebuildable normally.
I happened to some of these cars that will ruin the pumping load on the inside of the pump itself and also riparandole after a while it returns to the same, and in some I solved by mounting an electric pump from 0.10 bar (type prefilter) that part on the ignition and I have not had the pi? trouble, you are about 40 euro.
Instead, other models have sort of a solenoid valve connected to the bridge between the tubes of the intake and exhaust of the pump. Sometimes it freezes and does not allow the normal flow of diesel... when I have the delete and do a nice classic link.
Of course, I illlustrato my case... even if ? normal that not all are the same, but at least you have some idea further with which to work.