Abstract: Normally, the fuel pressure in a forward-flow fuel pipe leading to an internal-combustion engine is controlled in such a manner that a pressure regulator branches off a partial flow into a return-flow pipe which leads without pressure into a fuel tank. Normally, the branch-off pipe as well as the pressure regulator are arranged close to the internal-combustion engine in a closed-off engine compartment, for example, of a motor vehicle. However, as a result, not only the fuel flow returned by way of the return-flow pipe will heat up but, as a result of the waste heat of the internal-combustion engine, also the fuel volume situated in the fuel tank. As a remedy, it is suggested to arrange the branch-off pipe as well as the pressure regulator outside the engine compartment close to the fuel tank. A reversing valve as well as a rinsing pipe are also suggested in order to rinse, after the start of the internal-combustion engine, the injection strip with the complete fuel flow delivered by the pump.

Abstract: The invention is directed to a method of checking the tightness of a tank-venting apparatus for a motor vehicle having a fuel tank and an internal combustion engine including a lambda controller and an air intake pipe. The tank-venting apparatus includes an adsorption filter, a supply line interconnecting the adsorption filter and the fuel tank, a connecting line interconnecting the adsorption filter and the intake pipe and a tank-venting valve mounted in the connecting line between the adsorption filter and the intake pipe. The method includes the steps of: measuring the pressure difference between pressure in the tank and ambient pressure; when the tank-venting valve is opened, determining whether the pressure difference increases above a threshold value and whether a lean correction by the lambda controller is required; and, drawing the conclusion that the tank-venting apparatus leaks when neither a lean correction is determined nor the pressure difference exceeds the threshold value.