Hot engine starting problem 914F

In the meanwhile I know the answer. This afternoon I had a phonecall from a very kind Technician of Franz.

He told me that when the engine is very hot and you shut of the engine that the fueltemperature in the bowls begin to rise.

The temperature may reach as high as 90 till 100 degrees Celsius. The fuel in the bowls evaporate. Wenn you try to restart the engine after some time there will be a tremendous increase of fuelvapor in the bowls. Too much for the small rubber carb. deflate hoses. Consequence: the pressure in the bowls rises and fuel  will be injected in the carbs. Due to too much fuel in the carbs. the engine won't start.

Solution: start without fuelpumps. The 914F has two electric fuelpumps. Disconnect the fuse of the main pump. Start the engine and after 20 seconds press the fuse of the main fuelpump to connect it to the generator. After that you may connect the auxillary pump.

And use octane 98!

Kind Regards,

Gerard Hanstede.

The other thing you can do is to turn off the fuel pumps and then switch off the fuel for 30-45 seconds before shutting down - this will reduce the amount of fuel vaporization in the carbs and improve starting - it works for me.

Fabulous good idea! I am gonna try it.

Thanks.

The starting of 914F is very tricky, it shouldn't be, I am also suffering from such type of problems, mostly i succeed to start my stemme aircraft with rotax 914 F engine but with tricks. A recent experience is very intrusting , as I engage the starting key in rotary switch starter motor refuse to start, I jumped out of cock pit and turn the prope about 4 to 5 time by hand and again try for start and aircraft started and till now I am astonished how it happened.