Hi guys, really hoping for some advice here. Cut the long story short, reversing from a parking slot while putting window down. At exactly the time the window regulator goes and the car stops. RAC mechanic said it was due to faulty HPFP. Had that changed earlier today, tiny bits of shredded metal inside old HPFP. Car still wouldn't start after replacing the pump. Any suggestions what could be the problem? Thank you

Hi, I have never worked on an A5 but the principles are the same as most other VAG diesels I once had to help a mate of mine with 14 plate superb which had just cut out for no apparent reason so I plugged it in it came up with a code for the HPFP having low pressure so this seemed the obvious answer, before he rushed off to spend £400 on a new one it suddenly occurs to me that the car may have a lift pump in the tank so we tested it by taking the supply pipe off of the HPFP and then placing the end in a bowl turned the ignition on with the pipe in the bowl and NOTHING the lift pump was not working which is why the low pressure code came up the high pressure pump was not receiving fuel from the tank, we changed the lift pump £105 and away it went.

With regard to the shredded bits if they were gold in colour they all do that its brass from the core of the pump which under normal circumstances finds its way back to the fuel filter via the pump return pipe so it sits on the outside of the element where it cant do any damage as it cant get through the walls of the element because it is to dense, depending on the milage it is not a bad shout changing the high pressure pump as I have seen some real horror stories where people have left them until they rattle fit to bust and the car runs badly due to the wear fluctuations in the pump. advise don't run the engine whilst checking the lift pump as running dry will kill the new HP just ignition on no feet on pedals you only need the dash lights on.

Steve.