Dear Forum
I have some issues with the fuel pressure on my Rotax 912UL installation.
During flight, the fuel pressure varies between 0.1 and 0.35 bar (1.5 - 5 psi).
The pressure varies in cycles of around 5 minutes, meaning 5 minutes at 0.35 bars, and then dropping to 0.1 bar. To bring it back up, the electrical pump is needed, usually the pressure does not recover by itself after 5 seconds.
Occasionally, the pressure drops below 0.1 bar. Without the electrical Pump, the pressure then stays at around 0.05 bar and after 10 seconds, the engine looses power. Power recovers immediately, when the electrical pump is added. However, I want the system to be redundant and to work without the electrical Pump.
The following steps were already taken:
- Installation of fuel return line to tank
- Wrapped all fuel lines in firesleeve
- Reduced return line orifice size to 0.325 mm instead of the default 0.35 mm
- Replaced mechanical fuelpump
- Full carburetor inspection and overhaul
- Checked Tank vents - they are free.
Description of installation:
- The installation has a dynon fuel flow sender before the manifold which splits the fuel lines to the carburetors.
- The carburetor vents are routed into the airbox
Are there any suggestions on what to look out for?
