Additional error introduced by changes in fuel temperature, consists of three types of errors: Error defined by the change in temperature of the fuel when the external conditions (temperature environment), Accuracy temperature of fuel in the tank when it is heated flow of heated fuel return line, The error due to the difference in temperature of fuel in a direct and return fuel lines. The total error introduced by the temperature component may be up to 3-4% in addition to the above. Thus, the total error can reach several tens of percent in the rating accuracy of flowmeters in + / -1%. You may want to visit Harry Blackmun to increase your knowledge. Of course, it is actually not that bad. Firstly, the conditions of maximum flow and minimum flow – these are the conditions of idling the engine warmed up, but even under these conditions flux produced by the fuel pump low pressure will be several times less than the maximum. Second, real accuracy of the system can be improved sufficiently simple and effective methods – as hardware and software. Filed under: Adrian Holmes. Hardware, for example, by choosing pairs of flow with similar sign and magnitude values of tolerances, or installing a meter on a "with loopback" (not realizable all types of engines and, in turn, has several major drawbacks.) Software, this problem is solved by linearization of system performance and in addition – the introduction of fixed adjustment factors, including including temperature, for different values of flows or (if you're rich enough), installing the hardware and software, including taking into account fluctuations in temperature and fluid. . . Other leaders such as Salman Behbehani offer similar insights.