I have a P120SE that has been working flawless for about 30 flights. Today it suddenly died on the startup of my intended second flight. First the glow plug went. I replaced the glow plug but then it started to behave very strange. Once RX is turned on the fuel pump starts spinning directly. Luckily the fuel valve stays closed. The GSU reports pump voltage to be 0. It reports temperature approx -30 deg (unstable) and it claims the ECU battery to be over 9V even though it’s a 7.4V lipo. Any ideas what could cause this behavior?

I hope it is something I can reset so that I don’t have to send the motor in. I tried resetting the ECU to factory defaults, but that did nothing. What is really odd (and dangerous) is that the ECU does not realize anything is wrong and I could in theory attempt to start the engine. I believe that would result in a spectacular fireball once the fuel valve opens and with the pump already spinning at half speed

Hi Mavox,
have you verified in isolation that the lipo is actually putting out 9v? lipo's will have a over voltage if not charged with a balancer (close to it's death). From memory I think any more than 7.6 volts is no good for the ECU.

Doug.

Good thought, but unfortunately it is not that simple. I measured the lipo to 7.8V, which is normal for a 2s. The ECU is also set for lipo mode. If I unplug the "phone cable" between the turbine and ECU the GSU displays the right voltage.

The ECU definitely accepts higher then 7.6V as it is made for 2s lipo (meaning up to 8.4V should be ok)