General Motors has issued a service bulletin for its heavy-duty trucks Chevrolet Silverado 3500 HD and GMC Sierra 3500 HD for the years 2025 and 2026. The problem affects units with the 6.6L gasoline V8 engine and dual tank system. The vehicles may stop due to lack of fuel even though the rear tank still has it, while the gauge reads empty. GM admits the failure but, without a clear cause, does not authorize repairs.
The Complexity of the Dual System and the Search for the Root Cause 🔍
The technical bulletin suggests that the problem lies in the fuel transfer between the front and rear tanks. This system, which should maintain a constant flow to the engine, appears not to work as designed. GM engineers are investigating whether the failure is in the software, the level sensors, or the transfer pump. Until they identify the exact component, the company will not release a repair procedure or replacement parts.
The Official Solution: the Eternal Full Tank 🤦♂️
While the engineers search for the root of the problem, the advice for owners is simple: keep both tanks always full. This way, the transfer system doesn't have to work. In practice, GM recommends driving a heavy-duty work truck as if it were a collector's vehicle with the tank always topped up. A peculiar way to ensure you don't get stranded: spend more on gasoline before you have to pay for the repair.