Fuel Pressure / Flow

This may be useful to some people.

My Skyview system has two fuel transducers - inlet and outlet and computes engine fuel flow by the difference between them.

I found that if I temporarily disable the outlet transducer (by a software switch) the fuel flow reported by skyview is the actual flow through the system and recirculating.

I've measured the flow, voltage and pressure for what I hope may be a baseline to check fuel filter and pump performance at service intervals.

The figures without the engine running I got were:

main pump volts 13.0 pressure 44.9 psi 78 l/min

both pumps volts 13.0 pressure 46.4 psi 112 l/min

Auxiliary pump 13 volts pressure 44.6 psi 71 l/min

The operating manual says fuel pressure range is 40.6 - 46.4 psi continuous. Minimum flow according to the installation manual is 56 l/min.

The fuel pressure sensor is before the fine filter so the actual engine fuel rail pressure would be less but I am not sure if the rotax fuel pressure limits are for the rail or the pump outlet. Ideally perhaps we should measure both to calculate pressure drop across the filter.