Air in diesel fuel line Help!

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chilldown - 10 Oct 2007 22:33 GMT

Hello,

I have driven audi 80 TD on reserve diesel till it started missing.
Then I have tanked but it started giving white smoke. I thought that
filter is full of dirt so I changed the filter then I noticed that there is
air in the
lines so today I changed all rubber lines from filter to the pump but still
I can see air
in the lines and the white smoke is there.

My Qs is, Is it injector which is letting air? car is rough with reduced
power
and I already tried the injector cleaner with the fuel but so far no effect.

I also tried losening the diesel intake on the injectors to check if no RPM
reduces then
I can spot the faulty injector but all injectors effect the RPM so I guess
they are partially working.

What shoud be the next thing to check? It was all ok before I drove to empty
tank.

Any tip is much appriciated.

Thanks

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Madesio - 12 Oct 2007 04:49 GMT

> Hello,
>
[quoted text clipped - 22 lines]
>
> Thanks

Did you fill up the new filter with diesel fuel before you installed it?
Skipping that step in itself would create a fairly large air pocket.

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Madesio

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chilldown - 12 Oct 2007 13:24 GMT

I opened the filetr twice after that and yes I filled the filter everytime.
Somehow I noticed that vacuum is not building up.

>> Hello,
>>
[quoted text clipped - 25 lines]
> Did you fill up the new filter with diesel fuel before you installed it?
> Skipping that step in itself would create a fairly large air pocket.

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Madesio - 13 Oct 2007 06:42 GMT

> I opened the filetr twice after that and yes I filled the filter
> everytime. Somehow I noticed that vacuum is not building up.

I have a hard time understanding you, but from what i gather this
happened only after you filled up the tank? Your model is a little old
but most TDI's came equipped with an in-tank fuel transfer pump with a
check valve that often times became stuck open. It would also help to
rule out any damaged parts of the tank and lines up to the belt driven
pump that would be pulling in air as the pump runs.

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Madesio

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neeoup@googlemail.com - 14 Oct 2007 20:09 GMT

> Hello,
>
[quoted text clipped - 21 lines]
>
> Thanks

The fuel system needs bleeding. ( bleeding means letting the air out )
Look for the highest point on the fuel line, there may be a bleed
screw there.
On older diesels it is not a difficult thing to do, it was not always
necessary to have pressure in the system other than gravity. New eng'
fuel systems may be different and the system may need to be
pressurised and pressurised back to the pump to remove air in the
pump(s).
One way may be to have the engine running and start at the furthest
injector from the fuel pump or filter, bleed that one and work your
way back to the nearest injector to the pump. Opening and closing the
connections one at a time, waiting about 5 secs between opening and
closing the connections. You may need to do this several times. You
shall need something to soak up or catch the fuel in.

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