Have a long ranger 70 litre chassis tank fitted to my 1995 rx 4.2 diesel.Had the truck for 12 months,and in the first 6 months tank worked fine.These tanks use a vacuum system ,no transfer pump ,to send the extra fuel in the spare tank into the main.ie for every 10 litres you draw out your main( standard nissan tank) 10 litres approx gets drawn from the spare,if its avail.All lines blown out with comp air no blockages seemed present.checked and cleaned breather all good.Main tank uses a rubber seal on cap to create vacuum, that still seals really well,after 20kms you are really battling to release that pressure.emailed long ranger ,they said to check cap it may not be sealing ,lol thats the only thing to go wrong in the system they hinted.ok just about at wits end,so you my friends have a task,WOTS WRONG WITH THE BLOODY THING!. It sucks more than a charlie sheen lady friend ,all the lines ,breathers etc have been removed ,blown out ,replaced,and yet 70 litres in it this week will be 70 litres in 2 weeks time.The nissan tank works fine,gauge accurate etc, at this stage all comments will be considered ,so fire away.