100 series petrol fuel tank collapse

Old Valiants did the same. No emission control for vapour much at all and the tank breather was low down near rear axle. Drive on a clay road and the breather became blocked.
Tank volume decreased by at least 2/3 to only a very small amount. They were close to reading Full and Empty at the same time because it was a big wide flat tank and the bottom and top kissed each other.

Hi , you can find the fuel tank breather line on the charcoal canister, and blow through it to check if it is blocked,i would doubt there would be mud in the line as it is filtered, but could be a squashed line etc.

I think it will be more than likely the ball valves in the charcoal canister, rusted up,not uncommon, or the VCV (vacuum control valve) on the inlet manifold.
The whole system will need to be checked, a Gregory's work shop manual has the test/check procedure,well my 80 series manual dose.

Basically the charcoal canister stores fuel vapour,from the fuel tank and when the engine is started and running temp the VCV valve opens and the stored fumes are drawn into the engine.
Landcrusier charcoal canisters arn't cheap, a simple fix is to block the vacuum lines on the manifold, remove the breather line to tank from the charcoal canister,
and put a small inline fuel filter from a lawn mower or similar on the line and a length of fuel line and vent it down under the car.

**Note the charcoal canister is part of the emissions system so.may affect your road worthy, if any one ever dose look??
Unless you do the modification so it looks like it is still operational.
not unlike the many EGR deletes done on diesel engines!!!

canister-replace-or-remove

Rob

mud wasps, bloody nuisance!