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 injection nozzle for supplying fuel to an internal combustion engine includes a fuel pressure actuated valve member which moves into a chamber when it is lifted from its seating. The displacement of fuel in the chamber is served by a spring biased plunger which forms part of an electrical switch.

Abstract: An apparatus for providing an indication of a change in the dielectric constant of a fluid comprises a pair of electrodes at least one of which in use is surrounded by the fluid, an oscillator operable to charge and discharge the capacitors formed by the electrodes, the frequency of oscillation of the oscillator being dependent upon the voltage developed across one of the capacitors, and means responsive to the difference in the voltages developed across the capacitors.