Incorrect fuel readings

[stevensr34 Senior Member Find all posts View Profile Close stevensr34]

Of interest was that the fuel gauge dropped to just under half before switching to the sub tank(90L LIGHT ON).The sub tank holds 87L ONLY.As anyone noticed the same readings from their gauge

Hold on a moment. You have the wrong idea about how the fuel gauges work:

When totally full i.e. both tanks are full, the 90litre light is off and the fuel gauge reads the TOTAL of BOTH tanks.
The car uses up the second tank first.
When the second tank is approaching empty, the fuel gauge reads closer and closer to half full.
When the second tank reaches empty, the 90litre light comes on, and the fuel gauge now reads the amount left in the main tank ONLY.

This means that as the second tank hits empty, the gauge needle suddenly goes from 1/2 full to completely full, and at the same time the 90litre light comes on to indicate it is reading only one tank now...

[showtime Lurker Find all posts View Profile Close showtime]

Cool SUB tank first then main tank