Common Rail seems to be a big problem on all makes. For example I know a bloke who was very low on fuel when he got to work at the haulage company where he is a driver. The boss gave him some white diesel as used for the HGVs but the container used had previously held truck cleaner (detergent) Shortly afterwards the Citroen Picasso's high pressure pump failed. Traces of truck cleaner have no effect whatsoever on the Simms type inline pumps fitted to the HGVs, the problem is the new technology and ULSD which does not lubricate very well. Recently I was asked to look at an Iveco Ford lorry which had beccome a non-runner. Allegedly it had been ailing for quite a while so its owner replaced the lift pump. It has never run since and its highly likely that the high pressure pump will have failed. If one has the misfortune to own a common-rail vehicle it may be worth buying some two cycle engine oil and adding this to the fuel. Even a ratio of 100:1 or less will help. The oil is legal to burn in engines so they can't touch you for it. If two cycle oil is bought in 25 litre drums at the farmers supply store the cost will be reduced somewhat. Good luck.

Re the metal shards, presumably the shards are steel? If so it should be possible to trap these with a high powered neodymium magnet. Not rocket science is it?