What is So Special About the Chevy Volt Gas Tank?

The Chevy Volt offers a special pressure-sealed gas tank:

For the last several decades, new vehicles have been equipped with charcoal canisters to trap evaporating gasoline and then feed it back to the engine. Since the Volt’s engine may not fire up for extended periods, hydrocarbons potentially could build up in the canister, so the sealed tank contains the vapor. The extra pressure meant that a lightweight steel tank had to replace the lightweight plastic tanks used in most modern vehicles.

Volt engineers and supplier Spectra Premium Inc. developed the tank from 1.4 millimeter thick hot-dip tin-zinc coated steel to resist corrosion from both inside and outside. Despite the strength of the tank, it has a mechanical pressure relief valve that begins opening at 3.5 psi and a vacuum relief that opens at -2.3 psi, levels that are rarely exceeded.

Even with a tank that resists fuel vapors escaping or humidity getting in, the gas inside still needs to be used up and replenished periodically. That’s where the Volt’s “maintenance mode” comes in. If the engine hasn’t started after six weeks, the powertrain controller sends a message to the driver telling him the engine needs to run for maintenance.

Volt drivers can defer the engine maintenance mode for up to 24 hours, after which the engine will run for a while on its own to use up some of the gas and keep the internals lubricated and ready for use. If a driver manages to go a full year between fill-ups, the fuel maintenance mode will run the engine until the old gas is used up or the driver adds fresh fuel.

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Learn more about the Chevrolet Volt at Tyrrell-Doyle Chevrolet.