Well the old Magna is just wonderful, nice new sound system and all, but something funny has just happened with the fuel guage.

I filled right up a week or so ago, and have done around 265 kms since. At first I thought that maybe I'd not filled up completely at other times when the guage stayed resolutely above "F", but 265kms later, it's still there!!!

All the other instruments and systems are working fine, just the fuel guage is off the scale.

Any ideas?

It seems your fuel gauge decided to go to heaven. You can do a simple check to find the problem.

NOTE: Following is the procedure for TH model, use it as a guide only. Someone with TR workshop manual would be more helpful.

Disconnect the fuel gauge connector, should be under cover plate, under rear seat cushion.
Connect a test light to the harness side connector. Someone who can post a picture could do you a favor because you will see where fuel gauge and earth pins are.
Turn the ignition switch to ON.

If test light is illuminated (gauge needle is not moving) - replace the fuel gauge
If test light is illuminated (gauge needle is moving) - replace the fuel gauge
If test light is not illuminated (gauge needle is not moving) - repair the harness

If you remove fuel sender unit from the tank you can check float movement and hight.
You can also check resistance between fuel gauge pin and ground pin. Standard value (TH sedan) at the highest point is 4 plus/minus 1 ohms, at the lowest point 107 plus/minus 1 ohms. Resistance value should change smoothly when moving float slowly between highest and lowest point.

Thanks for the prompt reply; I shall dive under the back seat and have a go....

A little bit later....

There's nothing even vaguely electrical under the rear seat cushion....

When you remove the cushion, is there square lid (160x160mm) held by four screws? If it is, remove it and connector and supply hose should be right there.
I believe TR and TH use the same platform. That does not necessarily mean that fuel tank is the same, but one would assume they are. Procedure to check the fuel gauge should be similar if not the same as on TH.
I do not have access to TR workshop manual, someone who does could help you more.

Assuming often doesn't work. TR tank is 64 litres and fuel sender is on the side of the tank. Check this thread.

http://www.aussiemagna.com/forums/showthread.php?t=44154&highlight=fuel+tank

Ok, I've had a look in the boot, and right up at the back of the boot, and at floor level is what looks like wires going through a rubber grommet, down to the fuel tank.

All that said, if it is the gauge that is crook, how easy/expensive is it to replace???

Sorry to be pedantic, but can I ask, then, based on the fact that this seems to be a well-known problem.....

Do I need to replace;

1. The sender in the tank?

2. The actual fuel gauge in the dash panel, or

3. The whole dash panel (gauge cannot be separated from???)

4. The sender AND the gauge?

I've been working on my own cars and bikes for nearly 40 years, so I know my way round spanners and stuff, but I don't want to replace something and find out I should have replaced something else :D

try the fuel sender first

i know my is a tl magna but had that problem 1 month ago just replace the fuel sender unit.

Thank you for the replies, folks. Now for the fun part.

This morning after a brisk run up Macquarie Pass I noticed that the fuel gauge was working again :shock:

I can only assume that the sender unit was stuck (?) and that the cornering dislodged whatever was impeding it, because now the gauge is reading correctly.

Cars, who can understand 'em???