The fuel compartment is in the same place as the other Storage compartments but it has a fuel icon. It opens the same as the storage compartment which is by default Left Click.
The compartment has a slightly different texture, it has a hole in the bottom which is probably so the fuel can go through, Though there is no visable hole on any fuel canister.
The fuel compartment also looks blue. This is so you can right click the box to put the Gas Canister in, if you have changed your controls then it may not be left click.
