Petrol Gauge - Why does it not register?

[sideways]

I have had a problem since I purchased my boxster (2.7 - 03)with the fuel gauge.Intermittently I will stick in say 25 quid worth of fuel, and it does not register on the gauge ( Well not until the next day anyway)
I initially reported this to the garage (Porsche Main Dealer)who advised that unless I always fill it up fully every time, I may experience problems with the gauge readings, and that it resets itself? every night to establish the correct level, hence why after 24 hours it reads correctly.
I don't know that much about the in's and out ot porsche fuel units, but that does't sound right to me.
Anyways after speaking to someone different (At the same garage) he acknowledged that this was a common problem and that it would be resolved be replacing the sender unit.
They did this, and well.... Its still the same
Anyone had similar prob that could shed any light on it?

[soopdragon]

Mine does the same if I put less than 1/4 tank in. I tend to just fill it up nowadays.

[dewisant]

The dealer tld me that this might happen when I collected my car, if I didn't lock it after filling up. Apparently locking the car resets the system.....

[SarasDad]

If the fuel level is low enough to trigger the low fuel level warning light, the float sticks to bottom of the tank. After refuelling, wait a while or drive over sleeping policement etc, the float frees itself and all is well.
Porsche are aware of the issue, but probably don't want to change every fuel tank !

Moral : don't run the fuel level down.