Continuing fuel problems
 

Afternoon all.

Firstly a big thanks to all that helped me identify where the fuel pump control module was located - the garage I had it at were properly perplexed!

So, they fitted it and all was well again, for about three weeks when the day following a successful 350 mile round trip to Plymouth the car cut out again in exactly the same way as before. I managed to get it recovered to the same garage who have had it a week now and have achieved nothing. Their diagnostics is telling them there is no problem at all, everything is running fine, they left it running for an hour, all good, then when reversing out of the garage it cut out on them!!

Beaten they've just sidelined my car and have been working on everyone elses so today I jumped back in my car (they left it on the road in a trading estate!) and drove home, no problems.

Does anyone have any ideas what could be causing this very intermittent problem whereby the engine will cut out and will turn over but won't start due to no fuel delivery for about an hour but will then start up and drive fine again?

It's had a brand new, audi sourced fuel pump control module less than a month ago which was showing as faulty when it did it before. The only other thing that has happened to the car is the front plenum chamber drain holes clogged up leading to a small leak into passenger footwell but as part of getting the fuel pump module replaced this was cleaned out thoroughly and nothing has leaked since.

Any clues or ideas most welcome. Kinda at the point where if this isn't sorted and put to bed soon I'm just going to get it fixed and sell the car :(

Does anyone know roughly how much new fuel pumps would be for a 4.2 fsi? I see there's two in the tank and am just wondering if they're not hugely expensive whether it's worth just getting them both replaced (along with the fuel filter).

Is the fuel filter accessed from the top of the tank per the pumps or is it under the car where they usually are?

Scrub that, just seen, £210 each x 2!!

Maybe worth fully diagnosing rather than just replacing both in that case!

Damn, back to square 1!

So, checking on Audiworld they're suggesting that the left pump is used to prime the right pump, transfer fuel from left to right holds in the tank and to increase fuel supply at higher loads (above 3k)

So as a quick check tonight I started the car (first time) and it quickly sat down to a nice idle, but then when revving it sputtered above 3k and stopped dead at 4k.

How much fuel is in the tank? If it's the transfer pump then it doesn't usually show a problem above 1/4 tank or so.

Just over half a tank. So you're not thinking that's the problem then?

There's a detailed process to test the pumps on these in the tech dump Dave.

Have a look through the D3 common fault section for the tech dump

Thanks Delboy, I'll take a nosey after work tonight.

CHeers

Dave

Foudn the tech section and the pdf docs thanks.

There's a lotta specialist tools listed, of which I have none! Have printed the necessary pages and may well end up taking the car back to the garage with diagrams in hand!

Was hoping it was something I could check!

May still have a look tonight and see if there's something I can do to make myself feel a little more useful (hate relying on garages - especially when they're busy & slow & can't find out what's wrong!)

So, got close enough to each fuel pump to hear them both running whilst the engine was idling but the rough running still persists.

However, out of curiousity I took a video of the car starting up (from warm), blipping it and then on WOT where again the engine revved only to 4k. Video is linked below - is it me or is that an awful lot of steam and water coming from the exhausts?

This problem started around the time that I got a leak in the passenger (left side) footwell owing to clogged drain plugs in the plenum chamber (now cleared) - could they be related?

http://vid688.photobucket.com/albums...psmmyiobli.mp4