High-G FJR Junkie!
Join Date: Oct 2005
Location: Australia No fixed address
I have had a careful read of both the Owners, and Service manuals for the FJR. Neither manual explains how the fuel flow is measured, so I assume that there is no dedicated fuel flow measuring device in the system, or they would have mentioned it.
So, how is fuel flow measured? Well, the only useful data that I can think of, which is available to the computer, is "Time" from the bike's clock, and a count of fuel injector pulses, and their pulse duration. If the computer knows how much fuel an injector will pass in X amount of time, at a certain fuel pressure, it can then calculate the total fuel flow.
Now that the computer has calculated fuel flow, you only have to add distance traveled, from the odometer, to calculate fuel consumption.
So, there are a number of places where errors can creep into this system. These being, the condition and calibration of the injectors, fuel pressure, fuel density and temperature, accuracy of the odometer, accuracy of the timing (unlikely), and accuracy of the initial calibration data supplied to the computer. Also of course, the accuracy of the fuel station pump enters into this calculation, as does the accuracy of your refill, are you refilling to exactly the same point every time?
While the condition of other components in the engine, and loading of the bike, will affect fuel consumption, they will not affect the accuracy of the fuel consumption measurement/calculation.
FJR Models owned from new, 2001, 2003, 2006, 2009, 2011, 2014.
Last edited by Bernie; 03-02-2019 at 06:00 AM.