A fluid supply system is provided, especially for delivering liquid hydrocarbon to a fuel-operated vehicle heater or to a reformer. The system includes a fluid reservoir (12), a first fluid line (28) from the fluid reservoir (12) to an on-off valve (30), a second fluid line (32) from the on-off valve (30) to a first system area (14) to be fed with fluid, and a third fluid line (34) from the on-off valve (30) to the reservoir (12). The on-off valve (30) establishes a connection between the first fluid line (28) and the second fluid line (32) in a first valve position and establishes a connection between the second fluid line (32) and the third fluid line (34) in a second valve position. A first fluid delivery arrangement (26) is provided for delivering fluid from the reservoir (12) into the second fluid line (12). A second fluid delivery arrangement (20, 24) is provided for delivering fluid from the third fluid line (34) into the reservoir (12).