Abstract: A low pressure fuel supply system supplies fuel which tends partially to solidify at low temperatures and whose viscosity increases with decreasing temperature, from a fuel tank along a supply line, through a filter, to a fuel injection pump. A fuel recirculating circuit for recirculating fuel warmed by the injection pump extends from a return outlet of the injection pump, along a path extending through the filter to the injection pump inlet. A permanent bleed pipe extends to the fuel tank from the portion of the recirculating circuit between the injection pump return outlet and the filter. The flow-resistance-determining dimensions of the permanent bleed pipe are such that the pipe presents increasing resistance to the flow of fuel therein with decreasing fuel temperature. It therefore carries little flow at low temperatures of the fuel therein, most of the warmed fuel from the injection pump return outlet being directed into the filter.

Abstract: A fuel heater for heating fuel flowing in the fuel system of an internal combustion engine has an annular heating chamber in which is mounted a heating element formed from a material having a non-linear positive temperature coefficient of resistance. The element defines an upwardly extending flow passage and the heater includes a cup-shaped support member having a central aperture and an annular baffle plate 25 which forms the upper wall of the chamber. Cold fuel is led through gaps at the outer edge of the baffle plate and flows along the base wall of the chamber and then upwardly through the flow passage of the element. The heated fuel flows from the chamber through a space defined between an upwardly extending lid of the support member and a depending tubular element of the baffle plate.

Abstract: A fuel system for a compression ignition engine includes a high pressure pump to which fuel is supplied through a filter by a low pressure pump. A fuel heater is provided to supply heat to the fuel. Fuel is returned from the housing of the high pressure pump through a conduit which includes in a valve housing a restricted orifice. The valve housing also includes temperature responsive means which when the fuel temperature is low reduces the size of the orifice.