Thanks.

I have assembled it again. The last run seemed better yesterday although start max. temp reached to 800 degrees. I raised the fuel level (it always belowed the engine before and is higher than fuel line inlet) when rotor hung at 31K rmp then rotor dramaticly ran up to idle speed. However the engine still had a aglow and flame tail cone with EGT 760 degrees. I pushed throttle a little after stabilizing for a few seconds and the engine speed increased to 100K rmp while EGT decreased to 620 degrees that eliminated the tail flame. But EGT got back to above 700 degrees and flame came out of tail again when throttle restored to idle.

This phenomenon should be caused by bigger gap between turbine blade tip and NGV shroud, right?

Another thing is whether fuel level should be above the engine fuel line inlet during running.

You said ECU controlling of EGT is right. High EGT makes engine hang start. But why do the fuel level affect engine start?