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D2 - Fuel and Exhausts Everything to do with getting fuel into the engine, and fumes back out again

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Old 3rd July 2021, 02:21 PM
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Ronin Ronin is offline
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Default Car not starting with less than half a tank

So after replacing the fuel pump the car starts misfiring and slowly dies... This happened today while en route to a house viewing..

Last month the car wouldn't start as well with less than half a tank so I thought it was the fuel pump so I replaced it along with 2 o rings, 1 large and 1 small...

Any ideas what this could be before I set this car on fire?

I really don't have any more patience or willingness to pour money and time into it...
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Last edited by Ronin; 3rd July 2021 at 02:31 PM.
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Old 3rd July 2021, 03:48 PM
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Some food for thought here:

When the engine stopped fuel level was a little bit less then half, i walked to petrol station and got 10.8l of fuel and put it into the car, i had a little bit more than half showing.

The V6 has an 80l tank

I then drove to petrol station and filled the tank to the max with 47.5l of fuel...

So lets say i had 50l in the tank when i topped the car up with 2x5l canisters, i then drove to and filled up to the max with another 47.5L, this would equal to 97.5L of fuel which is 17.5l above what the V6 is supposed to be able able to carry and 7.5l what the V8 (90l) tank capacity is...

Do i have a faulty fuel level sensor here?
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Old 3rd July 2021, 04:11 PM
ainarssems ainarssems is offline
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Probably 2 things going on there.

1. Your fuel guage does not seem to be very accurate.
2. Fuel pump unit is tricky to seat properly to get the suction jet pumps working and sucking up fuel from the other side of tank. Usually it cuts out about1/4-1/3 but your guage seems to be wrong as well. Could be that your dash has wrong coding translating data from sensors incorrectly, one of the sensors could be faulty, extra resistance in wiring connections or maybe it needs a bit of adaption. From memory there should be +/- 15% adaption to gauge reading in adaption.

So to summarise when gauge is reading 50% it's actually 35% and at this point it cannot get fuel from the other side of tank because the pump is not seated correctly
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Old 3rd July 2021, 04:47 PM
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can the fuel level adaptaion be done with vcds? I can't find the procedure on their website.
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Old 3rd July 2021, 06:10 PM
ainarssems ainarssems is offline
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Quote:
Originally Posted by Ronin View Post
can the fuel level adaptaion be done with vcds? I can't find the procedure on their website.
I am not sure about D2, it's been a while.

If you go in 17-instruments, then adaptation and go through the channels it should come up somewhere. Definitely done it on similar vintage C5 A6, I can check ElsaWin later when I get home
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Old 3rd July 2021, 06:18 PM
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Thanks for this. I will also look up the correct cluster coding for a v6 with quattro as this also may affect it..
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Old 3rd July 2021, 07:31 PM
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UK models all have the 90 litre tank.
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Old 4th July 2021, 08:37 AM
ainarssems ainarssems is offline
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Pdf's from Elsa attached, channel 32 for adaptation. And from 2002 channel 33 also can be used for full indicator adjustment.
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File Type: pdf testing gauge.pdf (90.5 KB, 123 views)
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Old 4th July 2021, 10:59 AM
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Quote:
Originally Posted by ainarssems View Post
Fuel pump unit is tricky to seat properly to get the suction jet pumps working and sucking up fuel from the other side of tank. Usually it cuts out about1/4-1/3 but your guage seems to be wrong as well.
It does sound exactly like the same problem that several others have had here of an incorrectly seated fuel pump.
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Old 4th July 2021, 02:03 PM
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Quote:
Originally Posted by MikkiJayne View Post
UK models all have the 90 litre tank.
In the manual it says 80 for the V6 and VCDS is reporting 82... all this makes no sense
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