Passat TDI very hard to start after being sat couple weeks

[billbofagends]

Hi folks,

I've found a problem with my Passat Sport TDI. If it leave it a week or so with no use then it's a nightmare to start. It turns over fine but won't fire. This week I went to drive it and spent 30 mins or so trying to start it and in the end had to get a second battery involved as the it was getting pretty flat. Eventually it fired and once running ran absolutely fine and no problems once driving about. At the time the ambient temp was around 15 deg C so not exactly cold. The following morning, started no problem at all (temp more like 5 deg C). I've had this happen a few times now and it's when it gets left several days or more. I can't see that it can be the glow plugs; I can hear the fuel pump whirring away in the tank and it's driving fine once running. Are there any check valves in the fuel lines that could fail that could mean I'm losing residual fuel pressure somewhere and then sucking air? I changed the fuel filter last year so that should be OK. Any advice would be appreciated.

Cheers