Have a fire that is kinda confusing. The fire is at a gas tank of a 2007 Buick LaCrosse. Fire patterns and fire effects place the point of origin at the rear of the fuel tank between the under body of the vehicle and tank itself. There is a recall of some 2006-2007's because a bonding layer of the fuel tank was omitted. GM says that this tank is not included in the recall. The vehicle had not been operated for approximately ten hours prior to the fire event. The only electrical ignition sources in the area are the power supply for the fuel pump and two low voltage wires that run to brake pad wear sensors on the right and left rear tires. With the damage being isolated between the fuel tank and under body I can not see an external ignition source initiating the fire event.

Any ideas??