Mca coding HELPPPPPP

Can anyone tell me why it is impossible to get mca coding to run a hovercraft rental buieness when the fuel setup is the same as a dive rib,

both hovercraft hov pod and a dive rib have fuel tanks under the seat but ribs can be coded for buisness but hovercraft cant????????

Any and all advice most welcome even more so if you have a solution to this problem