Does the on board computer read correct with the amount of miles you have left in your tank, regardless of what the fuel gauge reads?
Thats a bummer, have you done the fault check???Could there be a fuel sender sensor that is failing???
I have the same problem with my YJ. I put £80 in, the gauge falls really quickly and 240 miles later it splutters to a halt
If i put 50 quids worth of diesal in my Cherokee ( a full tank ) i can get almost 500 miles out of it before it needs a refill....Of course living in Poland makes a bit of difference , and i do have to replace the odd cylinder head and other assorted bits on route....