I have a Weil McLain cg boiler that has pilot and the entropic igniter is constantly sparking. It has a mercury flame senser on the gas valve. Is this senser not working to allow the gas valve to open fully?
Do you have the installation manual for your boiler(also available online)? It will contain some diagnostic procedures to follow in order to find the source of the problem.
Probably the pilot orifice has become blocked, and without the pilot lighting, the gas valve will not open.--NBC