912iSpower,
Fuel flow is not one of the published limits in the Rotax Owner's manual. As RW pointed out, the 912iS fuel flow is determined by fuel mapping in the ECU and air density. Mechanically speaking, there are two things that govern the amount of fuel delivered to each cylinder; the length of time that the injector is open (pulse width), and the fuel pressure at the injector rails. The ECU controls the pulse width, and the fuel pressure is controlled by the Rotax fuel pressure regulator mounted at the outlet of the 2/4 cylinder fuel rail. The fuel pressure limits are published as a minimum of 2.8 bar (40.61 PSI) and a maximum of 3.2 bar (46.41 PSI). These pressures are in reference to airbox pressure, not ambient pressure.
The ECU has no way of knowing the actual fuel rail pressure, it assumes it's within the specified limits. I have always believed that the mixture would be a bit richer if the pressure was at the high end of the scale, and a bit leaner if at the low end of the scale, but Rotax has obviously figured out that acceptable range. Has your fuel pressure changed? If not, I would say reset your fuel flow redline up a bit and keep an eye on it.
