Greeting from the south Pacific. Our 2005 310, hull number 326, has decided to run incredibly economically, the fuel guage will not budge off reading full, despite how much fuel we have used. We cannot find any loose wires at either the tank or the instrument end. Any ideas please?
the easiest way to check is to remove the center wire from the send unit at the tank... does the gauge return to empty?...
if yes, the sender is faulty. OR... the sense wire from the gauge has grounded somewhere in its run to the the sender.
if no, the gauge is faulty....
a properly matched/working gauge and sender will show empty with the sender wire disconnected.... it will show full if the wire goes directly to ground.... (theoretically, it could very well work opposite, with the direct grounded sense wire showing on the gauge as empty, but i have NEVER seen this)
with it connected to the center post on the sender, it will show where the arm is pointing in the tank...
the gauge works on a variable ground from the tank sending unit... as the float arm moves up or down, so does the resistence.
the sender is like a mini rheostat with the float/arm controlling where the contact is made on the windings... the gauge measures this resistance and displays it somewhere between the empty and full marks....
BUT, even though you will usually find the problem somewhere by doing the above troubleshooting, it would be a good idea at some point to make sure the grounds at the gauge and the sender is good, and the continuity is not broken in either wire on the run to the sender.... and check for a fuse in the gauge hot wire.... make sure its still good.
it can all be checked very easily with a multimeter....