Fuel Temperature Sensor

A typical unit pump is equipped with a fuel temperature sensor. The fuel temperature will affect the fuel density, which will then affect the fuel injection. When the fuel temperature increases, the fuel density increases correspondingly while the actual amount of the injected fuel decreases, with the engine power being affected.

In the mechanical line pump or proportioning pump, there are, more or less problems caused by fuel density. Electronic control unit pump system, therefore, adopts the fuel temperature sensor. The ECU will control the opening and closing time of the electromagnetic valve to control the quantity of fuel injection according to the fuel temperature, eliminating the influence of fuel temperature on fuel injection.

In the case of the common rail system, the common rail pipe -- an oil storage container -- is adopted. The fuel from the high pressure pump enters into the common rail pipe, the pressure of the pipe is then increased to the range of 250 to 1800 bar. The liquid is compressed to eliminate the influence of fuel density, so the common rail system can have no fuel temperature sensor. But some common rail systems are also installed with fuel temperature sensors, such as the Japanese-powered ECD -U2 common rail system. Some cars are suffering from insufficient power after starting the engine, but the situation gets better after resting or cooling down the engine. Such failures may be related to fuel temperature sensor protection. The plunger leakage or other problems cause high fuel temperature, so the engine reduces it torque in order to protect the engine or the unit pump.