Ok so the motor starts and runs fine for the last few months.

Flew it the otherday and it was all fine.
Went to fly again and no start.
Checked the ecu and got "plug open".

Changed the plug, it started and flew.
Went to start again later and nothing.

Will not ignite the gas.

Changed plugs twice, still no gas ignition.

Changed the start gas settings up and down, still nothing.
Took the motor out of the plane and put it on a test stand.

Still no start.
Varied gas and glow settings, no help.

Checked all gas lines, even under the cowling. All good. Put air through the lines, no restrictions anywhere.

Held a torch to the rear of the motor during a start attempt. Gas ignites then blows out torch.
Still will not ignite on it's own.

WHats next? Any ideas?