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Information on Engine Shut Off During Fuel Transfer Between Fuel Tanks

Subject:Information on Engine Shut Off During Fuel Transfer Between Fuel Tanks

Models:2003-2004 Chevrolet Kodiak C4500/C5500 Series
2003-2004 GMC Topkick C4500/C5500 Series
with 8.1L Gas Engine (VIN G -- RPO L18) and Dual Fuel Tanks



For the above listed vehicles, observe the following information in order to prevent the engine from stalling or running out of fuel.

The fuel transfer system software monitors the time the transfer pump runs to move 3.78 L (1 gallon) of fuel from the rear tank to the front tank. The software knows the fuel has been transferred by monitoring both sending unit level outputs to the controller. The fuel level in the rear tank should drop the equivalent of 3.78 L (1 gallon) as the level in the front tank increases by 3.78 L (1 gallon). The fuel transfer must occur in less than two minutes.

The fuel transfer system works well as long as fuel is not added to the vehicle during the fuel transfer. If the customer is refueling the vehicle with the engine running and fuel transfer is commanded ON by the controller, one of the sending unit outputs will either be rising when it should be lowering (filling the rear tank) or rising faster than expected (filling the front tank). This will cause the transfer system to think there is a problem with the transfer and will disable the fuel transfer system for the remainder of the current ignition cycle. If the customer continues to operate the vehicle, eventually the front (primary) fuel tank will run out of fuel without warning the customer. The fuel gauge indicates the average reading of both tanks and because there may be fuel in the rear tank and no fuel in the front tank, the gauge will indicate that there is still fuel in the vehicle.

In order to prevent the above circumstances from occurring, the customer MUST turn off the engine (as required by law) when refueling the vehicle and leave the ignition key in the OFF position.