I have a rotax 912 iS in a Zenith CH750. I have a Skyview Classic. The aircraft time in service is about 40 hours. I changed the fuel injection pressure sensor from a 101716 - 000 50 psi unit to a 1013757-000 unit supplied by Dynon before first flight last November in accordance with Dynon SB dated June 4 2020.
Last flight I started getting sporadic "high Fuel pressure" alarms (>50 psi). Thinking I may have fuel filter clogging, I prepared to change fuel filters. Before I did that, I checked the system to get a baseline pressure this morning by running the injection pump without starting the engine. The indicated fuel pressure reading was 49.2 psi which is way over the allowable limit of 46.4 in normal operation. When I shut down the pump the pressure did not drop to zero as it should but remained at 5.7 psi. I confirmed this behaviour a few times. I checked the EMS sensor setup and it shows that I selected the correct sensor running in differential mode. I tried changing to a non differential mode and skyview indicated the same thing - 5.7 psi when fuel pressure should be zero. I checked Skyview data from my first flights eleven months ago and fuel pressure returned to zero when the system was switched off. It doesn't seem to do that now. I checked MAP behaviour and it is normal.
Unless there is a physical blockage in the fuel return line, which I have not checked but doubt, or a corrupted sensor file, which I have not checked, it appears that the sensor has failed. I note that subtracting the offset from the indicated pressure puts the fuel pressure where it should be prior to startup at about 44.6 psi.
What else should I do to try and isolate this fault?
Last flight I started getting sporadic "high Fuel pressure" alarms (>50 psi). Thinking I may have fuel filter clogging, I prepared to change fuel filters. Before I did that, I checked the system to get a baseline pressure this morning by running the injection pump without starting the engine. The indicated fuel pressure reading was 49.2 psi which is way over the allowable limit of 46.4 in normal operation. When I shut down the pump the pressure did not drop to zero as it should but remained at 5.7 psi. I confirmed this behaviour a few times. I checked the EMS sensor setup and it shows that I selected the correct sensor running in differential mode. I tried changing to a non differential mode and skyview indicated the same thing - 5.7 psi when fuel pressure should be zero. I checked Skyview data from my first flights eleven months ago and fuel pressure returned to zero when the system was switched off. It doesn't seem to do that now. I checked MAP behaviour and it is normal.
Unless there is a physical blockage in the fuel return line, which I have not checked but doubt, or a corrupted sensor file, which I have not checked, it appears that the sensor has failed. I note that subtracting the offset from the indicated pressure puts the fuel pressure where it should be prior to startup at about 44.6 psi.
What else should I do to try and isolate this fault?
