fuel gauge

[Eddie987]

my boxster 987 3.4s has developed a fault with the fuel gauge display. it shows empty when I still half a tank full.
any ideas which could solve this problem.?
Eddie

 

[Motorhead]

Very difficult to diagnose the fault just from your description Eddie. It could be the gauge itself or the sender unit/module and it's probably best to get a diagnostic check to see if any error codes are flagged up rather than just swopping components.

You could try filling the tank to the brim and see if the fault clears itself.

Jeff

 

[Glyn]

This is probably just the tank float sensor sticking.
The sensor works by changing the resistance from full earth (full tank on the gauge) to no earth (empty reading on gauge)
To eliminate other electrical issues just remove the electrical connection, switch on the ignition, get someone to observe the gauge and touch the electrical connection to earth - If the person watching the gauge reports the needle going to a full tank position then you know the fault is solely with the tank float unit.

You could try filling the tank - and the pressure on the float would force the sweeping arm to rise - and unsticking it may solve the issue, or you may have a fault with the variable resistor itself (the tank float unit windings) and therefore you would need to swap out the tank float unit.

The system works just like a ballcock in a toilet system.

 

[Eddie987]

thank you for your replies guys. i did fill the tank to the top and guess what, it now seems to be working properly.
eddie