7000+hour ingame... aux tank ?
Hum... how about that...
You learn something new every day.
There are two tanks: primary (for FSD jumps) and aux (for running your powerplant, and with it everything else). Both are refueled when refueling at a station. Using a scoop only the primary is filled. When your primary is empty, you can't jump anywhere. When the aux is empty it'll try to re-fill from the primary (so that can leave you stranded!) and if that is impossible it'll de-activate the powerplant. Your ships is now dead and depending on your life support you'll have a few minutes of time to ask for help.
Have read the whole topic, keep in mind that the aux tank size is different for every fuel tank class/size, (although not depleted by jumps, but adds to ship mass) there is also a hidden value specific to each ship.
For example your Crusader's aux tanks holds 0.77 tonnes (A Sidy holds 0.25 tonnes) If you have modules active with a combined high tonne per hour fuel burn, you can run out very quickly and end up on life support if the main was consumed during your jumps.
There is no fixed figure on burn rate, all depends on your individual setup and what you have left running. Burn rate is displayed above the fuel gauge when fuel is available and will only vary if the ship is undocked.
My ship has an aux of .77t, and it ran out in nine minutes of effective game time since the last refuel (removing witchspace time as no fuel is consumed during it). In other words, while all my ships (from DBX to my Corvette) run between 1-2.5t/hr, for this not to be a bug my ship must consume well over
5t/hr. Or between 2-5x more than any other ship I have. And considering that going from my explo DBX to my combat corvette adds only 1.5t/hr, I don't see how I can get the extra +-4t/hr in my crusader...
(if anyone can load up a crusader with guardian shield boosters and post the consumption, that'd be grand!)