Thanks all for the replies, we've tried the usual stuff like blowing thru the fuel lines, check them for leaks etc....

Sounds like the Glowplug may be feasible then, because one thing I did notice, the gunk coming from the exhaust on it's succesful flight was VERY black, like what you wipe off the dipstick when you're checking the engine oil on your car.

Any suggestions of what plug would be suitable on the Evolution (please don't say the one that's on it cos they are a swine to get hold of)