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VW Passat 2.5 V6 AKN - Fuel pump fault - Fixed #

Posted by Peter Rainsley on February 17, 2012, 9:51 pm

Year of Manufacture *: 2003
Engine Size and Code *: 2.5 V6 AKN
( Optional ) Scanner Used: VCDS
( Optional) Fault Codes: No DTC's

There is no fuel at the filter. I have followed the system back to the in-tank pump where I have 12 volts/2.5 amps on crank. The pump appears to be working, but the fuel appears to be dumped back into the tank via a Y connection going to a green pipe that disappears into the depths of the tank. We have now removed the pump unit, with Y connection, and three of us cannot work out how the system of pipes, strainers and pick-ups work. Does anyone have a working knowledge of this overcomplicated lift pump? TIA,
Peter

Re: VW Passat

Posted by David Davies <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5218' width='330' height='300' border=0 style='border:none;'> on February 18, 2012, 2:33 pm, in reply to "VW Passat"
David Davies

Peter,
Here is a brief extract from Elsawin.
Description of function:

In order to empty the fuel tank as much as possible, a two-part reservoir housing with electric fuel pump is located in the tank.

The electric fuel pump delivers fuel from the outer part of the reservoir housing to a closed container (reservoir chamber) in the inner part of the reservoir housing. The injection pump of the diesel direct injection system draws fuel from this chamber.

In addition, the electric fuel pump forces fuel via a Y connection into a suction-jet pump below on the reservoir housing. The suction-jet pump ensures that the outer part of the reservoir housing is always filled with fuel.

In order to guarantee reliable engine operation, the chamber in the inner part of the reservoir housing must always be filled with fuel. If the fuel level threatens to sink due to an empty tank, the low fuel level sender -G210 gives a signal to shut off the injection system.

Re: VW Passat

Posted by Mark Carter <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on February 18, 2012, 3:12 pm, in reply to "Re: VW Passat"
Mark Carter

Hi Peter,

I have been here before, the important part of David's post is;
>> The injection pump of the diesel direct injection system draws fuel from this chamber <<

What tests have you done with regard to this fault?

Mark

Modern cars, Its all wizardry and witchcraft

Re: VW Passat

Posted by Peter Rainsley <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5418' width='330' height='300' border=0 style='border:none;'> on February 19, 2012, 2:12 pm, in reply to "Re: VW Passat"
Peter Rainsley

David and Mark,
Thanks for that insight. I was called to the car by a garage customer as a non-starter. It had logged 00542, needle lift sensor, which was indeed open circuit. Although I didn't think this was the cause for the non-start, it felt pointless to continue until such an obvious fault was rectified. They eventually fitted 'another' injector, and the code cleared, but still no start. Further investigation revealed no fuel at the filter. As the wiring diagram showed an electric pump, I naively assumed it to be a pressure pump, and my investigations went down that line. A case of incomplete knowledge. So, Mark, is my next test on the suction side of the filter head/pump, or is there another piece of VW wizardry waiting to trip me up?
TIA,
Peter

Re: VW Passat

Hi Peter,

If it helps, I would start by Checking the pump drive belt (separate to the cam belt)I have known them to strip, but the engine still sounds normal(cranking)because the main belt is still in "Time".

After that I would be checking the pumps ability to draw against a restriction and if good I would probably set up a donner fuel supply just to prove the vehicle will start.

After that I would follow the circuit back to the tank repairing the fuel line as needed.

Regards Mark

Modern cars, Its all wizardry and witchcraft

Re: VW Passat

Posted by Peter Rainsley <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5418' width='330' height='300' border=0 style='border:none;'> on February 19, 2012, 8:10 pm, in reply to "Re: VW Passat"
Peter Rainsley

Thanks a lot for that Mark, that is a very comprehensive worksheet for next week

,
regards,
Peter

Fixed #

Posted by Peter Rainsley on February 21, 2012, 7:46 pm, in reply to "Re: VW Passat"
Message modified by board administrator February 23, 2012, 2:53 pm

Mark,
Spot on! Even removing the covers it was not apparent until the engine was nudged around and the stripped part of the belt spanned the two pulleys. The question is, what caused it? The belt had been changed within the garage's memory. The conclusion is that the pump must have frozen up in the severe weather they get up on the Roman Wall,
many thanks,
Peter

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