I am investigating a fire in a 200 freightliner dump truck. It has a Caterpillar C-12 diesel engine. Approximately 2 1/2 months prior to the fire the owner noticed smoke coming from one of three batteries. The plastic around the positive post was melting. He replaced the battery. Approximately 2 weeks prior to the fire he installed a new starter. The starter would not disengage. On the day of the fire the truck started out with 80 gallons of fuel. Approximately 5 hours later the engine sputtered and stopped. The truck had run out of fuel. He estimates that it had only used 30 gallons of fuel and 50 gallons had leaked out. Diesel fuel had sprayed out onto the front of the engine. It was towed back to its home location. The owner examined the fuel line but could not find a leak. He pressurized the metal fuel line from the transfer pump but it held pressure. He put approximately 15 gallons of fuel in the tank and tried to start the truck. The starter cranked but the engine would not fire. The air condioner had also gone out sometime previous to the fire. It was scheduled to go in that week for repair. The AC compressor had locked up the year before and had been replaced. The owner had gone into his house and then later saw light flickering through the window. He went out and the engine compartment was on fire. He tried to fight it with a garden hose but was not very successful. He lives in a very rural area and it took awhile fore the local volunteer fire department to arrive. The heaviest damage was on the driver side of the engine and the cab was totally gutted. The positive battery cable from the battery for the first couple feet was in good shape. The cable then passed through a bushing going toward the engine. From the bushing on the cable sustained heavy damage and the heat in the cable appears internal. The conductor was heavily oxidized green and the insulation was charred. This part of the cable was not near the fire area. It was under the cab toward the rear of the cab. The area of origin appears to be where the starter and ECM were located. The truck had broken down approximately 12:00 p.m. The fire was at approximately 9:30 p.m. I am looking for ideas of what might have started the fire.