Fuel gauge and fuel smell problems (audi 100)

Hello,
In my Audi 500 (South African version of the European Audi 100), there is quite a strong fuel smell, especially in the boot, after the care was filled up.
In addition, the fuel gauge doesn't work properly any more. When the tank is full, it shows just under 3/4. When the tank is absolutely empty, it still shows more than 1/4, as I found out when the car stopped (luckily 50m from home). The warning display and beep for an empty tank also doesn't work any more.
Thanks for any suggestions,
Christoph
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Gas smell near the rear of the type 44s usually is caused by leaking fuel lines due to corrosion under the rubber mounting fittings.
If the problem with the gage started at the same time as the fuel smell the problem might be in the tank / Fuel pump which has the fuel level sensor in close position. Still, odd that these would be related.
Tony '91 100q 5spd
Christoph Bollig wrote:

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Hi Tony,
Thanks for your reply:

Are those inside or outside the car? How do I get to them?1

I think they changed a valve near the fuel pump not too long ago. It might have to do with this. Is the fuel pump and gauge accesible from inside the car, or from underneath? The fuems seem to come into the car. I can't smell anything outside the car, when it is standing, but when I open the boot, I get a lot of smell coming out (when the tank is full, otherwise it's no problem).
I will have to also enquire with the garage who did the valve. The problem is that it's a bit away, and I have trouble to get there during the time they are open.
Thanks again,
Christoph
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Christoph Bollig wrote:

Under the car you can follow the fuel line along the frame on the passenger side of the car. You will find rubber mounts all along there. The problem is that water accumulates in there and can rust through the line.

The valve is probably the fuel pressure check valve. On some years it is part of the fuel pump. On others it is a separate black plastic device close to the tank but separate from it. May be it just needs to be tightened. The fuel pressure in these cars is high (60 + psi AFAIK)
Is the fuel pump and gauge accesible from

Crawl into your trunk : ) and there is a plate under the carpet right behind the back of the rear seat. Removing this plate gives access to the in-tank fuel pump and the sending arm for the fuel gage. You don't want to do this unless your tank is almost empty.
The fuems seem to come into the

You may also want to check if there is a leak in the tank filler pipe.

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