If the main burner is coming on before the pilot lights then you are lucky it does not light, If you have had a gas valve and pcb fitted already then I would suspect that it is only the pilot gas that it is on. if you have already had a new ignition lead, then the only other 2 things left which are the cheapest and the ones i would have changed first are the spark electrode and pilot injector. does the spark look good when it is trying to light.
gary.wright53@googlemail.com
August 2007