Abstract: A fuel filter for an internal combustion engine of a motor vehicle, comprising a divisible housing having a fuel inlet opening and an outflow opening, a replaceable ring filter element (3) mounted in the housing so that flow can pass through it radially from the outside to the inside, having an end disk on one end, namely a first end disk (13) and a second end disk, an alignment of the longitudinal axis of the ring filter element (3) that is upright during filter operation, an outflow channel (5) which leads from the bottom to the top out of the fuel outflow opening in the radial interior of the ring filter element (3), carrying filtered fuel away in a tube (4), a centrally arranged vent channel (6) that leads outward from the bottom and is closed at the top, with a throttle opening (7) in the upper closure, whereby this throttle opening (7) opens into the clean space or the crude space of the filter, should be designed so that the internal combustion engine cannot be operated when the ring filter insert

Abstract: An internal combustion engine, in a motor vehicle, has a fuel filter system in a fuel line leading to the internal combustion engine. The operation of this motor vehicle exclusively with fuel of filtered quality is ensured. To this end, a valve is provided inside the fuel line preventing the internal combustion engine from being started when the fuel is unfiltered.

Abstract: In the case of an internal combustion engine, in particular in a motor vehicle, having a fuel filter system in a fuel line (9?) leading to the internal combustion engine, it that operation of this motor exclusively with fuel of filtered quality is ensured. To this end, a valve (14) is provided inside the fuel line (9?), preventing the internal combustion engine from being started when the fuel is unfiltered.