Fuel Gauge / Sender Unit.

My fuel gauge on my 1999 TD5 110 Defender has suddenly gone from half a tank to very empty. There is a problem with the gauge or level sensor.
Before I start pulling bits off to see where the problem is, has anyone had to do the same??
Wondering if there could be a common fault.
Thanks

On TD5s the fuel sender is part of the pump, located in the tank, and handily accessed from the top of the tank!
In my 90 I opted to cut an access panel in the floor when I replaced my pump, with a non-genuine item... the gauge never went below 1/2... finally got around to swapping the fuel sender off my old broken pump - made easier by having a handy access hatch in the floor - this was very easy, as the terminals were just spade connections so the sender just uncliped, no soldering required.
If your pump has been changed for a non-genuine item, this may be the cause of your problem?
I still monitor my mileage after each fill... and get nervous by about 400miles

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If you start bending the arm, it will never give a true reading. Check the earth.