what you need to do is see what that 40 amp fuse powers. then unplug all those components 1 at a time. if it still pops after unplugging them all then you have a frayed/cut wire somewhere touching ground. look for any cut wires or melted wires etc... not if you say unplug the ignitor and the fuse stops blowing. you have a bad ignitor that is shorted to ground internally and it will need to be replaced etc...