Fuel tank mod not working

I'm trying to make half of Covet out of box utility version simply by removing the trailer, but the problem is that fuel tank is on the trailer. So I'm making a mod that will let it having a tank without having the trailer by creating a new fuel tank that would be in slot of the trailer. The part appears in the part tree, but when config is assembled the engine does not start and the gauge shows that the tank is empty (however in tuning tab initial fuel amount is full).
I've mostly copied from covet_boxutility and covet_boxutility_fueltank. I'm not using any model, so there is no nodes or beams. What am I missing?

Code:

{
"covet_trailerback_fueltank": {
    "information":{
        "authors":"Serg",
        "name":"Fuel Tank",
        "value":150,
    },
    "slotType" : "covet_trailerback",

    "variables": [
        ["name", "type", "unit", "category", "default", "min", "max", "title", "description"],
        ["$fuel_R", "range", "L", "Fueltank", 25, 0, 25, "Fuel Volume", "Initial fuel volume", {"stepDis":0.5,"subCategory":"Right"}],
    ],
    "energyStorage": [
        ["type", "name"],
        ["fuelTank", "fueltank_B"],
    ],
    "fueltank_B": {
        "energyType":"gasoline",
        "fuelCapacity": 25,
        "startingFuelCapacity": "$fuel_R",
        "fuel": {"[engineGroup]:":["fuel_R"]},
        "breakTriggerBeam": [],
    },
},
}

 

Thanks a lot, this helped.
Pretty much uncontrollable though... just as expected)
So here's the mod: