Huh. Fuel gauge is permanently showing empty (actually below the E on my gauge), turning ignition on causes the needle to flicker but basically sits in the same position as when off. Tank is full of fuel. Tested the gauge and associated wiring and that's all fine.

While driving about the needle has shot up to where it should be (on a couple of journeys) but when come to drive it next the needle is sulking again.

Looks like the tank is gonna have to come off. Ugh.

SAS

Try the sender first before you drop the tank.
There are also some connections underneath just above the tank that you might be able to get to, perhaps they aren't connecting properly.

The sender is on top of the tank, no way to get to it or the connections without dropping the tank. I've looked up the back end of the tunnel and can see the wires branching off from the loom and disappearing between tank n tub but that's all. Access is very limited.

I'm guessing its either the sender gone or just the connection(s) to it have corroded etc, but the only way to find out is tank off.

SAS

Take some pics while you are down there to help us all when it happens to ours! Good luck.

As above

Hope you get your G Force Meter, sorry, fuel gauge sorted

Small update. Properly established it is not the gauge itself or any of the wiring at that end so it will be a tank off job. Removed the rear shelf interior trim panels to find access to the four tank securing bolts, which ironically only turned out to be hiding one. The rearmost left bolt (which has a tube spacer between tank flange and outside of tub) is accessed through the big hole in the top of rear shelf (it also gives access to the bottom LHS engine frame mount point). The other three tank mount bolts are under the handbrake cover, one either side of the tunnel and one just above where the RHS engine steady bar is bolted. The shelf panels and the hump on the drivers side give access to the various fuel filler/breather pipes.

I've only undone all the panels and left them loose in place for the moment cos ran out of time today and wanted to leave car drivable.

Will need to;
1 remove gear rods
2 drain coolant & remove hoses
3 slide forwards or cut off rear section of radiator tubes
4 unbolt clutch slave cylinder and move out of way (hose goes under tank)
5 undo fuel filler hoses
6 undo four bolts and drop tank

Pfffffff...

That's quite a faff --- dreading it happening to my car. Whilst its all apart if you can afford it why not change the pump as well. Do it once do it right.
Steve

The pump has never caused a problem so I see no reason to mess with it, it's only the sender at issue which is a separate unit. I suspect it could be just corroded contacts rather than the unit itself.

Tank has been removed. Managed to withdraw the ally rad tubes out the back of car without having to undo hard to get at P clip bolts. FYI coolant capacity is about 5.5/6 litres.
Used a ladder with wood blocks under tank and jack at one end to lower tank down after unbolting - worked well.

It was the connectors on top of the sender unit causing the problem. Earth connector tag on sender is steel and very rusty, signal connector was copper so not as bad. Emptied the tank and stood it on end tipped over slightly causing the float to flop to the top of tank - DVM used to test the resistance which measured exactly as if tank was full. Tank flat down also gave correct 'empty' reading so sender unit itself is fine.

Soldered a short fly lead to the cleaned sender tags, heatshrinked and will be painted/undersealed for further protection. Will cut off the old spades on loom side and use new ones positioned so they can be accessed under car without removing tank. Fuel pump connector is proper sealed type so will be left alone.

Tank will be cleaned, rust removed, repainted etc. and then reinstalled.

While i've got the coolant system drained i'll probably renew some of the hoses and get rid of some of the many connections between long ally pipes and rad/engine. That'll be another post though...

Some pics on 'GTM Kit cars' Facebook https://www.facebook.com/media/set/?set ... 262&type=1

Good progress.

Its a bit of a faff getting the tank out so well worth giving it a proper clean up as you say, these original tanks are rare now. I painted mine with POR15 - brilliant stuff.

Tank cleaned, painted & reinstalled. Gauge now appears to work ok, still showing tank as empty though to be fair it actually is at the moment Need to get the cooling system sorted before I can go fill it up properly.