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aliw
14-01-2012, 08:04 PM
Hi all,
Whilst returing from the French Alps for our Chrismas Ski Hol, my 1999 Audi A4 2.5tdi Quattro Avant died on the French motorway (towing a caravan as well!!). Just prior to it stopping the glow plug light started flashing on the dash.
I checked a few things and the fuel primer bulb (retro-fitted) was empty, so she had run out of fuel...despite showing about 1/3 of a tank and 70 miles on the computer range (towing, so only doing 27mpg).
As we had filled up with cheap fuel in Luxembourg, I also had 2x20l jerry cans full of diesel with me. I put these in the tank, but the tank was overflowing before the second can was empty (38l ish) so I know the fuel gauge is correct (about 20l of diesel left in the tank when it stopped!).
Anyway, I couldn't bleed it at the side of the road, so called the breakdown service (had european cover!) and they eventually managed to bleed it and get us on our way again.
The day before this when we left the Alps, I started the car and started driving only to have the car fill up (from under the dash I think!) with electrical smoke!!! I checked everything I could but could not find anything not working or amiss, so drove on and had no further symptoms.
Now we are back home I have run feeds directly to the scavenge pump in the fuel tank, and it sounds as though it it pumping (drawing about 2.25A). I am now thinking that the smoke I had may have been a relay for the pump or something burning out, which I am going to check out tomorrow.
I have done some searching on the forum and people mention that the pump should run whilst cranking, and I assume that it should then run continuously when the engine is running (to keep the baffle housing/container that the injector pumps draws from full). Is this last statement correct???
If so does anyone know which relay and the location controls this pump?? I assume the ecu activates it??
Has anyone had any experience of these problems before and can let me know if I am missing anything?
If I can't get the feeds/relays sorted has anyone just ran the in tank pump continuously from an ignition controlled feed? Would there be any issues with this?

aliw
16-01-2012, 03:10 PM
I have started checking the circuit for the in tank fuel pump and am confused to say the least.
The Manual says position 28 "fuse S 228 off fuse carrier (left row, 5th large fuse from the top)" should protect the pump...I do not have one fitted here at all...just an empty slot!
The relay looks as though it has no set position and can be plonked anywhere by Audi "fuel pump relay in 13-point relay carrier (no fixed position)" !!!
I only have a few relays in this carrier and think I have identified the correct one (Red relay in Pos 8) as it comes in with the engine running and has the same colour (green/yellow) wire as at the fuel sender connector, although all the other wire colours on the relay are wrong! The relay is kicking in ok, there is 12v out of it but still nothing at the pump!
Do I have the wrong relay and info...it all looks standard and unmolested, but nothing is tying up with the manual!

aliw
16-01-2012, 11:03 PM
Ok, Schoolboy error, the diagram I had for the fuse box was for a LHD car, so a mirror image of the RHD putting fuse 28 on the other side of the board. Didn't notice the numbers on the fuse board in the fading light the other day. Checked the fuse and it was blown. Replaced it and pump is now working fine drawing about 3.5A at the fuse today. Relay was actually a grey one in position 6 in the 13 point relay carrier.
I can only put the fuse blowing due to the temperature being -10 deg C and maybe the diesel had started to thicken making the pump struggle. A lot of electrical smoke for a fuse blowing thought on the morning we left though!! Hopefully this is the end of this saga, but it'll take a bit before I trust it below 1/3 of a tank again!!

bagpipingandy
12-03-2012, 01:59 PM
I am having the same symptoms with my Allroad 2.5 quattro did you ever go below 1/3 tank again? did it occur again or did you solve the problem?

Andy

macscunge
16-03-2012, 08:20 PM
I had problems with my 2.5 tdi fuel supply. Make sure before changing in-tank fuel pump or anything else that there is absolutely no air getting into the fuel lines.