A fuel filter used with a supply of liquid fuel and with an engine has a housing formed with a filter chamber, with inlet and outlet ports respective connected to the supply and to the engine and opening into the chamber, and with a throughgoing return passage juxtaposed with the filter chamber and extending between a return-fuel inlet connected to the engine and a return-fuel outlet connected to the tank. A filter element is in the chamber between the inlet and outlet ports. Fuel moves in a circuit from the supply to the inlet port, then through the filter element in the chamber, then out the outlet port to the engine where a portion of the fuel is consumed and a portion of it is heated and flowed back to the return-fuel inlet, and then through the passage and out the return-fuel outlet to the supply.