I am currently flying in temps of zero to 5 degrees centigrade. The model lives in a warm house or warm car when not on the airfield. On Saturday I had a lot of trouble getting the engine to start the fuel pump but assumed it was due to low gas pressure not hitting the required temperature. Neverthless I had 8 flights. The next day the engine would not start the fuel pump at all. I connected the GDT and saw the gas temp was above the minimum and revs were good as well. I disconnected the fuel line and ran the primer function from the GDT but although I could hear a ringing noise from either the pump or ECU (they are next to one another) there was no movement of fuel. I connected the main turbine battery directly to the pump for a moment to break it free and it pumped fuel. After that the primer function on the GDT pumped fuel, and after that the engine started okay.

Engine has had around 100 starts so the pump is not old and should not be worn out. I wonder if oil congeals in the pump and makes it stick in cold temparatures? Any ideas?