Nitro Engine dies when take glow plug off

[Layloo9136]

Hi all

Its been a long time since I ran an RC car and the last ones I bought were off a mate so already run in.

Running in my Losi 8ight, took me best part of 8 hours to get the thing going and ran 1 tank through then it died when I topped it up.

Now I can get it going again but it dies as soon as I take the glow plug off, whether in 30 seconds or three minutes?

Why please?

Thank you