Your Mech will accept various kinds of items as fuel, from conventional Ship fuel isotopes, biofuels, Erchius all the way to Oil and even Power Cores. This functions as a quick and dirty way of assembling and reviewing your Mech Left-Click - Fuel Iconas well as refuelling it. To fuel your Mech, you must first have a Personal Tricorder.
It is still possible, however, to break your Mech, or use whatever life support systems it has available, ie, keep you from drowning or freezing to death. Should your Mech be low on fuel, a beeping sound will instantly play to remind you to refuel. Heavier mechs with good protection rating of 4 or higher gain a chance to shrug off smaller damage increments completely due to their natural toughness. Mass can influence a great number of things. Mech mass is determined by the mass of each part arms, head, legs, boosters, body of the vehicle.
Mechs have new features in FU distinct from the vanilla game but very close to the XS Mechs Modular Edition mod, which the code is based on.