Its been a long time since I played with a Walter or Gnome but a few first thoughts.( may be a bit confused with other engine systems )
Battery low voltage can lead to hot or hang starts.
Is PT output shaft loaded or locked govenor may try to overfuel ( I used to run Walters but always against rotorbrake )
Are you using Jet A1 or other fuels ?
Have you put any screening over intake ? ( you will need something )
Are your igniters set up correctly and giving off a really good spark.
Out of interest how are you going to harness the power of this thing?
Are you going to derate the engine like the RR 250 in the Y2K?
I must admit I have been having similar ideas if your name is a clue, but using a microturbine in a scooter ( a lot less power to soak up )
Have you tried any American sites, lots of people over there seem to be using similar turbines in tractors, boats etc.
Pm me if you need help anytime I live over the river.