Patent ID: 7256583
Filing Date: 2007-08-14
Classification: F02M,G01M

Abstract:
1. A device for testing seal tightness of a fuel tank system of a motor vehicle, wherein excess pressure is built up in the fuel tank system by an electrically operated pump and electric current consumption of the pump is compared to reference values in order to determine whether the seal tightness of the fuel tank system is sufficient, and wherein the fuel tank system comprises a filler neck with a locking fuel tank cap, the device comprising: a control line connected in parallel to a power supply line of the pump, the control line being guided across an electric tank cap switch, which has a different switch state when the filler neck is closed properly than when it is not closed properly; and an electric resistor installed in at least one of the control line and the power supply line; wherein, in the control and power supply lines an electric current develops, when the filler neck is not closed properly during operation of the pump, which allows a determination of the switch state of the tank cap switch.