2.9 S3 Fuel rail pressure

[White S3]

When should the fuel rail run at the reported 3 bar? On initial fuel pump prime before start, mine only reaches 1.5bar, when I manage to get the car running (by initially disconnecting 3 of the injectors) it then returns a pressure of 2-2.5bar at most.

What would cause it to runs below pressure?

This failing to start whether cold or hot is doing my head in!

Edited by White S3 on Friday 28th June 15:35

[phillpot]

White S3 said:

When should the fuel rail run at the reported 3 bar?

thought I'd read somewhere 30-40psi so 2-2.5 bar should be ok ?

[mep12345]

Mark,

I have a spare back pressure valve if you have the aluminium (rather than pressed steel) fuel rail that you could borrow if you like.

Let me know and I can bring back to Portsmouth any time you want but recognise your forthcoming availability (or lack of it)

Mark

[Maffe]

Found this in the manual for the fuel pressure thingy



Have you ched and double checked all conector and used electric cleaner on them?
Same for vaccum hoses?

[White S3]

Maffe,
Thanks for the info - something else to check. Starting to check for blockages anywhere but I would expect to be kangarooing down the road when driving once the engine is running. Issue really only manifests on starting (cold or hot).

Very interested in the "in tank" filter - anyone know what is in the little swirl pot on the underside of the tank? I have had a leak from there in the past so heavily gasketted and metal puttied to prevent the hint of vapour or catastrophic failure occurring.

Mark V.

Further to my last - Interesting turn of events, now the fuel pump seems to either take for ever to prime system (minutes rather then the previous few seconds) or doesn't stop running. I can hear fuel returning to the fuel pump. Would this indicate that pressure reg has now failed completely or to much pressure continuously? Car still won't start.

Edited by White S3 on Saturday 29th June 18:19