Theory Of Operation

The fuel transfer diagnostic is required to detect a blocked or missing fuel transfer hose which connects the primary and secondary fuel tanks. Once enough fuel has been transferred from the secondary tank and the secondary fuel pump has been on for a minimum amount of time, the primary fuel level is checked for the fuel level increase caused by the fuel transfer from the secondary tank. Since the engine is running, fuel consumed by the engine during the fuel transfer must be taken into consideration. Therefore, if the fuel level increase in the primary fuel tank is less than a calibrated threshold (minus the amount of fuel consumed during the transfer) a failure will set indicating a missing or blocked fuel transfer hose.