XRAY - Model racing cars

Yeah, I'm afraid your Futaba RX was too hot and "shut-down". Next time take the IR tempgun and measure the temperature. If I remember correctly the critical suht-down temperature is about ~65C .

Also, if I'm correct, the LRP LiPo RX Voltage Regulator (6V/5A) is total cr*p. Its not switching so-called UBEC regulator but a standard voltage regulator that converts the extra voltage to heat (wastes energy). It doesn't handle more than 2A continius current drain and HEATS. 6V/5A is nonsense. Consider getting a switching regulator - 22$ for Castle Creations UBEC is my recommendation. If you have closed radiobox then the heat from your LiPo regulator also makes things worse.

I'm running open radiobox at the moment. RX is put inside a condom or an airballoon, CC UBEC is taped to radio box wall and everything is held in the radio box by 3-4 rubberbands over the radiobox. I saved 20+ grams of weight (upper part of the radio box) and haven't yet had the Futaba receiver shut-down. I also used thick double sided tape and aluminum tape to heat-shield the radio box - a lot of heat comes through the chassis plate.