Fuel Gauge and Part Identification

[steve54]

Hi a bit of help required, the car concerned is 89 Tennis, the problem is the fuel gauge shows almost full when turned off and beyond full when ignition is on, it has been doing this intermittently for a number of years and only working very very rarely, I just fill the tank every 300 miles and I get away with it but I have now decided to get to the root of the problem.

I have tried to find the sender to test the wiring first ie ground the lead and reading the forum and Haynes manual it says there is a bung under the rear seat but when I lift it there is nothing there just 2 sound deadening panels.

Underneath the car to the front of the tank is a plug and socket clipped to the tank with 3 cables, brown, brown and black and one brown and red, my guess is these could go to the sender.

Under the wheel arch attached to the top of the fuel filler pipe is a part I don't recognise but may be relevant, something like a pneumatic relay with a small tube 7 or 8 mm going in then coming out and then going into the top of a small canister approx. 70mmx25mm  and out again. I don't know if this is all related but cannot find any reference to it in the Haynes manual.

I have taken photos with the intention to attach but notice the max size is 0.29mb and unfortunately they are 3mb.

I appreciate any help and sorry if I waffled on but wanted to give as much info as possible.

Thanks in advance.