A fuel system includes a cooling fuel supply line that conveys a flow of cooling fuel from a storage tank to a mixing device. An upstream fuel return line conveys a flow of heated fuel to the mixing device from an internal combustion engine. The flow of the heated fuel from the upstream fuel return line mixes with the flow of cooling fuel from the cooling fuel supply line in the mixing device to form a flow of mixed fuel. A downstream fuel return line conveys the flow of mixed fuel from the mixing device to the storage tank. The mixing device includes a flow restrictor operable to generate a low pressure zone relative to a fluid pressure of the flow of cooling fuel in the cooling fuel return line that draws the flow of the cooling fuel through the cooling fuel supply line and into the mixing device.