Case of the Month: Why did the Corvette burn?

May 1, 2016 by

The classic red 1977 Chevrolet Corvette was a total burn loss. What was the cause?

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The Corvette was to be shipped to Hawaii, so it was loaded on a trailer by a tow company and delivered to the port for shipping. While loading the vehicle on the trailer, the owner of the transport company smelled gasoline. After they arrived at the port, they attempted to restart the Corvette to drive it off the trailer and into a staging area. The car would not start, and the driver of the tow truck drained his jumper battery box trying to start the engine. He then obtained assistance from two of the port mechanics. They brought two more battery jumper boxes to the Corvette, and the engine was eventually started. The port workers reported that they saw a great amount of fluid leaking from the right side of the engine. One worker thought a radiator hose had come loose.

Just then the fire ignited, and the tow driver quickly exited the vehicle as smoke and flames came out of the supercharger opening in the hood. Two nearby fire extinguishers were unsuccessfully used up in an attempt to extinguish the fire. Four more fire extinguishers were then also used in a vain attempt to stop the fire. Eventually the fire department finally extinguished the fire.

Our expert inspected the vehicle at the port in the presence of our client (who represented the tow company) and the terminal manager. He observed that the engine compartment had been heavily modified. Aftermarket components included:

  • Weiand brand air scoop.
  • Holley double pumper carburetor.
  • Weiand brand Pro-Street supercharger and intake manifold.
  • Aftermarket fuel pump, filter, hoses, and fittings.
  • Edelbrock brand valve covers.
  • Aftermarket bracket assembly for the alternator and the power steering pump.
  • Tubular exhaust headers.
  • Numerous other small aftermarket components.

The fire consumed the fiberglass hood and front fenders. The fire damaged the front fascia, headlight assemblies, front tires and wheels, windshield, front portion of the driver’s door, right side door, door windows, roof assembly including the “T-tops”, rear deck, rear quarter panels, and upper center of the rear fascia.

As the fire moved rearward it consumed all of the interior combustibles. The heat of the fire also partially melted the top of the red Optima battery that was mounted behind the driver’s seat. The battery cables were equipped with inexpensive aftermarket battery terminals. No indications of pre-fire short-circuits were found on the battery cables, battery terminals, interior wiring harness routed to the stereo unit area, ignition switch, auxiliary power sources, or the heater, ventilation, and air conditioning controls.

The fire pattern indicated that the point of origin of the fire was at the right side of the engine compartment, and it damaged most of the rubber and plastic components in the engine compartment and melted some of the lightweight aluminum components.

The fuel system was heavily fire damaged. The modifications for the fuel supply system originated beneath the rear-mounted fuel tank. An aftermarket fuel pump had been mounted in an exposed position beneath the fuel tank with its power supply wires hanging loose under the rear bumper. The steel braid protected fuel hoses were held in place with plastic tie wraps with the hoses secured to the fuel pump and clear plastic fuel filter with worm drive hose clamps over the steel braid of the fuel hoses.

The fuel supply hose then connected to the stock steel fuel tube up to the lower right side of the engine compartment. Here another steel braided fuel hose brought the fuel to the fuel pressure regulator. The hose had been improperly secured by merely pushing it over the steel fuel supply tube; it was not secured with hose clamps.

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The other end of this fuel hose had come loose from the fuel pressure regulator. The fuel supply hose on the other side of the pressure regulator was also found to be loose and could easily slip over the hose nipple. The hose clamps were still in place over the rubber char on the hose from the fuel pressure regulator to the carburetor. The carburetor was partially melted.

The engine compartment electrical system was examined. The starter power cable was found loose at the starter terminal. A large melted short-circuit area was found on the end of this loose cable; this would have prevented full power from reaching the starter motor, which would contribute to the hard starting issues. Additionally, the arcing across the failed starter power cable connection quite possibly provided the spark that ignited the vapors from the leaking fuel. A naturally occurring spark from the spark plug wires could have also ignited the fuel vapors.

In summary, the services performed by the tow company did not cause the fire. The loose and missing fuel line hose clamps were the fire cause.

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