I,ll chime in here. But I will tell you, I have no real experience with this engine and pump only hear say knowledge. If this is the same pump as on our Fg649 Canters and numerous industrial uses (mini excavators and bobcats). Then apparently inside the pump there is a small PC board that sits in the diesel fuel and is not affect by the diesel. It is though affected by water (moister) in the fuel (the moister is attracted to the copper on the PC board ) and causes corrosion. Probably more on machines that do a fair bit of sitting around.
An Fg649 that I looked at buying a while back suffered from this problem and the pump was away for repair and they didn't have a time line for getting the pump repaired (by the diesel service). The part was to be supplied by Bosch.
Probably not much help,
Dan.