Air leaking back into fuel system when parked uphill

[drwint]

I have an 97 A6 with 2.5TDI 5 cylinder engine. I have had trouble starting it in the morning for a year and today it wouldn't start. It was parked facing uphill and the fuel seems to have drained out of the system and it couldn't pump it back until I got the car turned round to face downhill. Should there be a non return valve somewhere in the system to stop it being able to drain back? If so where and is it possible to replace it?

[Squirts]

The OP has no doubt sorted the problem but for anyone else accessing the forum, I'll bother to reply - my own car, a '96 Tdi has a NRV in the supply pipe, I think. If not the supply pipe, it's the return! This valve is situated in the pipework under the bonnet, on the bulkhead side of the filter. If a system is filling with air, one bodging way round is to fit a small electric Facet pump under the bonnet, actuated by a dash switch. If the car won't start, you can easily prime the system. Additionally, these little pumps have their own NRV. I fitted one years ago on a Mercedes with leaky O ring seals as a stopgap before I replaced them and it worked a treat. Always try and find out where the air is getting in, though.