... but if it's not too too old, the BU-353 is likely not the problem. Quite often, in CarPC setups, this type of issue is related to some RF interference (USB GPS too close to something, for example LCD display), or the length of USB extension cable (too long USB extension will reduce voltage. You may need powered USB hub), or just simply inferior location of the GPS receiver (GPS receivers need to see the sky in many directions to receive signals from several GPS satellites).