(Home) Fuel guage

After filling my tank to the neck, my fuel guage has read inaccurately. It reads full most of the time, occasionally falls for short periods then rises to full again. I drained 4 gallons out of the vehicle and it still read full. I then disconnected the electrical feed to the tank, switched on the ignition and watched the guage fall to empty. Reconnected the electrical feed and the guage stabilised at 3/4 full ( where I expected it to be ). However after 100 miles it still reads 3/4 full ( no its not the most economical Liteace in the world ) Disconnected and reconnected the electrical feed as above and the guage dropped to under 1/2 full.
Any ideas on what could be causing this problem and how to rectify it would be appreciated.

- (#9707) Stephen Judge, 19 Jul 03 8:46

sticking gauge needle perhaps? You haven't disturbed the dash recently by any chance?
Next time it does it, try giving the instruments a thump. Make you feel better if nothing else...

- (#9708) david miller, 19 Jul 03 9:02

I don't believe its the guage itself( Have spanked the dashboard quite hard, even swore at it, and nothing happened ), as it always wants to move up not down and only moves down if I disconnect the power supply to the tank, then switch ignition on ( fuel guage falls ) and then reconnect( fuel guage rises ).
Could it be something to do with the voltage regulator? But the temp guage is OK.
BTW There are 3 leads to the tank. Is there a seperate sensor for the low fuel warning light. Need to know in case I'm in jeopardy of running out.
- (#9709) stephen Judge, 19 Jul 03 15:37

i reckon its the earth or the multi pin plug on the top of the tank
The earth is provided by the two 12mm sicket sized bolts towards the front of the van on the tank seam - unscrew and clean - and the plug is on top . held in by a thumb barb . you dont need to drop the tank - just put your hand on the top surface and feel , i did my mates last week and it was very corroded . new connectors and dump the old plug

regards jim

- (#9710) j adgo, 19 Jul 03 15:43

Stephen, the gauge has two coils in it- one connected to the sender, one connected to ign. for response compensation. It's the difference between these that makes the gauge move (more current in the sender coil increases the reading). Jim might be right tho- give it a try. And the light has a seperate sender, yes. It's a thermistor. The fuel keeps it cool= high resistance, no fuel for cooling, heats up, resistance decreases, light goes on...

- (#9711) david miller, 20 Jul 03 2:57