You have answered your own question. The interference is only there when the fuel pump isn running. The Facet has a DC motor pump and this is causing the RF noise. IIRC the cube is an automotive product and has no EMI filtering.
At a rough guess a 470nF non polarised capacitor of at least 50Volts across the power feed to the pump (as close to the pump as possible) would make a significant improvement.
For general reading:
http://www.fightingrobots.co.uk/documents/emi.pdf