401 Fuel Gauge or Sender Problem.

[Geoff Kingston]

We finally have a working fuel gauge, we got the main earth problem sorted which gave us a good earth to the dash but we still could not get the test lamp illuminated properly off the terminal to the yellow wire only on the adjacent one, we were debating whether the gauge might be wired up incorrectly or defective when we realised that someone in the past had already swapped the position of the yellow wire round and got it wrong, we should have spotted it on the wiring diagram sooner but didn't, because everything looked original and undisturbed we were not expecting that problem , with the yellow wire now back on the correct terminal and ignition on the gauge went straight to full, movement at last!
We quickly confirmed this fault was due to a bad earth to the sender unit, using a temporary connection we had the gauge reading properly but the earth wire in the loom wasn't doing its job, we traced the problem to a break in the earth wire where it had been bolted to the body in front of the rear wheel, with a new terminal, nut and bolt and the mounting area cleaned we finally got the good earth we needed and all is now working as it should.
I am very grateful for everyone's input on this it has been a great help in solving the problem.
Geoff.